MIAMI – Standing before a luggage scale at Fort Lauderdale-Hollywood International Airport, Rita Coskey was not happy with Spirit Airlines.

As she struggled to lighten her overweight suitcase – and avoid total baggage fees of $63 – the 25-year-old New Yorker renewed her vow to avoid the low-fare, fee-intensive airline for future travel.

“I remember saying the same thing, I’ll never fly them again,” Coskey said. “When I saw it was cheap, I forgot all that.”

It’s not that CEO Ben Baldanza doesn’t care about such complaints. But, he wonders, what do customers like Coskey expect?

“No one gets surprised when you go into McDonald’s and don’t see filet mignon on the menu,” he said.

Spirit Airlines Inc. is unapologetically not filet mignon. The company prides itself on keeping costs low, offering the cheapest fares around and charging high fees for extras as basic as carry-on luggage and agent-printed boarding passes.

That low-cost ethos trickles all the way up to the company’s humble headquarters in Miramar, Fla., where there is no receptionist, employees take out their own trash and the overhead lights operate on a minimum number of light bulbs when they’re even used.

“We try to not spend money on things that our customers don’t really care about,” Baldanza said. “Our customers don’t care how nice my office is or how palatial our headquarters are.”

While alienating some fliers, the no-amenity strategy has kept the company profitable since 2007. Spirit saw a net income of $7.9 million for the three months that ended March 31 – a stretch when the country’s five biggest airlines reported a loss of more than $1 billion combined.

Despite a weaker-than-expected initial offering of public stock in late May, the company that uses SAVE as its stock symbol is earning admiration from Wall Street.

“SAVE is the newest business model in town with absolutely no frills, small enough to grow capacity by 17 percent per year through 2015, and even lower unit costs than (JetBlue) and (Southwest), which should enable SAVE to profitably stimulate demand in new/existing markets through discounting tickets 1/3 below competitors,” wrote Citigroup analyst Will Randow in a July 5 investment advice note.

Spirit’s business model may be relatively new, but the firm itself dates back nearly five decades, when it was founded as Clippert Trucking Company. Over the years, it became a charter tour operator, air charter and eventually a scheduled passenger airline called Spirit.

Spirit chose Fort Lauderdale-Hollywood International Airport as its base in 2004 because of its low costs and proximity to Caribbean and Latin American destinations. Today, the airline is Fort Lauderdale’s largest carrier, with 19 percent of total passenger traffic for the first five months of 2011.

The move to a low-cost approach came after investment management corporation Oaktree Capital Management gained control of the company following investments in 2004 and 2005. Indigo Partners, a private equity fund with stakes in five other discount airlines around the world including Tiger Airways, Volaris and Avianova, acquired a majority stake in 2006.

Spirit started shifting to a model the company calls “ultra low cost” after Indigo took majority ownership, using as an example Ireland’s much-criticized but historically successful budget carrier Ryanair. On Ryanair, base tickets may cost only a few dollars, but nearly everything else costs extra – including checked baggage, reserved seats and paying by means other than the company’s approved debit card.

For Spirit, a similar strategy has been the flight path to profits. Since 2006, non-ticket revenue per passenger flight segment has mushroomed 600 percent. That revenue includes Spirit’s credit card, annual subscription to a club that allows access to the lowest rates and sales of advertising aboard planes.

And yes, fees, where Spirit is the industry leader. It was one of the first U.S. carriers to charge for checked bags in 2007 – a practice that even many legacy carriers have since adopted. And in 2010, Spirit pioneered charges for carry-on bags too big to fit under the seat.

Last year, the airline ranked first among 20 carriers in fees as a percent of total operating revenue. According to government statistics, Spirit charged more than $104 million in bag and reservation change fees in 2010, accounting for 13.4 percent of its total operating revenue of nearly $780 million. All told, U.S. airlines last year collected almost $5.7 billion from those two categories of fees.

Recently, Spirit announced that boarding passes printed at the airport by an agent would cost $5 starting Nov. 1. But the airline emphasized that printing at home and at kiosks for the next year would be free, and base fares would be reduced by $5.

The fee-heavy strategy and other service practices related to Spirit’s tight cost structure have prompted rants on social media and user review sites such as Yelp. Complaints about long airport waits, delayed flights, poor service, cramped seats and fees for items as basic as water on a plane are common.

Countered Baldanza: “You’re going to think I’m a jerk when I say the next thing, but if you have some sort of medical condition that requires you take a certain pill at 2 in the afternoon and you’re going to be on the plane at 2 in the afternoon, I think it’s going to be OK to expect that people are going to be responsible enough to make sure that they can take that pill.” In other words, pay the $3 for a bottle of water on board, or bring your own – though you’ll need to purchase that after you pass through security.

Not all of its practices have passed government inspection, however. Spirit was ordered by the Department of Transportation to pay a $375,000 fine in 2009 for its procedures for bumping passengers from oversold flights and its handling of lost or damaged baggage, though the company only had to pay $215,000. The airline is now challenging some new DOT consumer protection rules.

“They don’t want to be loved,” said George Hobica, founder of travel site Airfarewatchdog.com. But, he said: “Nobody beats them pricewise – even with the fees.”

Still, when it comes to more extreme ideas floated by Ryanair CEO Michael O’Leary – such as charging for bathroom use and having passengers carry their own checked bags to the plane – Baldanza, who made $607,360 last year, says no.

“In terms of what we’re willing to charge for, it’s really when we can make something an option,” he said. “We’re not going to charge for bathrooms because we don’t think bathrooms are optional.”

Baldanza said he only considers adding fees that customers can avoid if they change behavior.

“If you behave in a way that saves Spirit money, we’ll let you save that money,” he said. “If you behave in a way that costs us money, then we’re going to charge you that incremental cost.”

In the past five years, he said, Spirit’s average base fare has dropped from $104 to $77 while fees have gone up from $5 to $35. The overall increase, he said, amounts to $3.

Robert Mann, president of airline industry analysis firm R.W. Mann & Company, gives Spirit credit for that trade-off. He said most airlines add costs without giving customers anything in return.

“When they talk about cutting the cost of something, a lot of that actually gets delivered to customers in the form of lower base fares,” he said.

Spirit uses the “ultra low cost” moniker to distinguish itself from low-cost airlines such as Southwest and JetBlue. Those airlines win customers with prices that are often – but not always – cheaper than larger legacy carriers and passenger-friendly perks such as free checked bags, TVs and comfy seats.

“On JetBlue you’re going to have more leg room and you’re going to be able to watch a TV, which are both very nice things,” Baldanza said. “But on Spirit, our fares are going to be lower.”

Spirit crams in the most seats allowed by the government, so they’re more fuel-efficient and cost-effective. But seat pitch is less than the industry average for economy class, and comfort is a secondary concern. Aircraft are utilized nearly 13 hours a day on average.

The bottom line, according to Citigroup’s Randow, is that Spirit’s cost per available seat mile is more than 30 percent lower than the industry average, six percent below Southwest’s and 24 percent lower than JetBlue’s. That math includes adjustments for stage length, or the length of an airline’s average flight.

Spirits now flies 35 planes – all Airbus A319, A320 or A321 models – to 46 U.S., Caribbean and Latin American destinations, and has another 33 aircraft on order for delivery by 2015. The average fleet age is four years, which keeps maintenance costs low for now. The company’s past model has been to lease its planes; Baldanza said Spirit hasn’t yet committed to how it will finance upcoming deliveries.

Future routes haven’t yet been announced, but Baldanza said the ideal destinations will already be served by airlines that charge high fares and operate at higher costs.

“When those are the case, we generally find that we can go in and lower the fares, stimulate the market, create more people flying,” he said. “We’re trying to grow the market with lower fares.”

The company is looking for balanced growth both in the U.S. and internationally; in June, the airline announced new routes from Las Vegas and Chicago as well as flights from Fort Lauderdale to Toluca, Mexico, and San Salvador, El Salvador.

Company filings with the U.S. Securities and Exchange Commission indicate that the Caribbean and Latin America are principal target growth markets for both leisure travelers and price-sensitive customers who want to visit friends and family back home.

That segment is key to an airline’s survival in rocky economic times, said Ray Neidl, aerospace specialist at investment bank brokerage Maxim Group.

“It’s the bottom economic strata; a lot of ethnic traffic that goes home that is very price-conscious,” Neidl said. “People want to go home, and they will pay, good times or bad.”

Corporate travelers whose companies might pay for travel or who just want a more comfortable flying experience are not Spirit’s key market.

Guys like Bruce Lamberto, on the other hand, fit their profile perfectly. He watches for sales, uses the Spirit credit card to earn mileage, and belongs to the $9 Fare Club so he can access the cheapest routes.

To avoid baggage fees, the City of Miami Beach employee carries a bag small enough to fit under the seat in front of him, which is free. And he keeps his expectations low – not a bad idea when the airline you fly had a 73.1 percent on-time performance in 2010, compared to an average of 79.8 percent for 18 U.S. carriers.

“It’s a trade-off,” Lamberto said. “You want to fly for cheap, that’s what you get for cheap.”

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