TULSA, Oklahoma - Allegiant Air is a small airline with big profits. In fact, it's continued to be one of the most profitable airlines in the industry, keeping itself in the black while other airlines struggled.

That's because of Allegiant's fee-heavy business model.

The only way to fly Allegiant without paying a fee is to buy your ticket in advance at the airport and pay cash, then carry on one personal item, no larger than a purse or a briefcase.

Allegiant Airlines has come to Tulsa, hoping to lure travelers to sunny Orlando, Florida.

But buyer beware: Allegiant is a low-cost airline, offering the round trip flights for less than $200, but it tacks on fees for everything.

According to FrequentFlier.com, Allegiant is the second worst airline for fees. The list of add-ons is lengthy.

How do you want to book your trip? By phone? That'll be $15 per person, per segment. So $30 a person roundtrip.

Booking online? Ten dollars per person each way.

Checking a bag? If you reserve a spot for your bag in advance, you'll pay $20 each way.

But if you wait until you get to the airport to check your bag, you could pay up to $75 each way. That's $150 roundtrip for each checked bag.

And if your bag is more than 40 pounds, tack on another 50 to 75 bucks, again per bag, each way.

Carry-ons will cost you, too--$13 each, each way if you book them in advance, up to $75 each, if you do it at the airport. Oh, and if you want to pick your seat, you'll have to shell out more--up to 75 dollars each time for that.

Even snacks and drinks will cost you, from a couple bucks to $13.

A spokesman for the airline, based out of Nevada, confirms those nickels and dimes make Allegiant profitable, but it also gives its passengers money-saving options.

"We don't charge a high base rate for your airfare, so a lot of our revenue is generated by our ancillary fees," the spokesman said.

But some customers aren't buying it.

The Better Business Bureau, where Allegiant is headquartered, has fielded 489 complaints about the company in the last three years.

A spokesperson says, while each complaint was addressed by the airline, only 89 of them were considered resolved by the consumer.

We should note, Allegiant is not alone in it's fee-heavy structure. Many airlines have embraced it as a way to survive.