By The Kiplinger Washington Editors May 1, 2012 Spirit and Allegiant airlines have taken a cue from European carrier Ryanair and adopted the a la carte model, discounting tickets but charging fees for everything under the sun. The airlines charge the typical $35 to $45 fee at the airport to check a bag (Spirit is upping its fee to as much as $100 in November). Spirit dings you $50 for a carry-on bag, and Allegiant charges $35 ($15 less if you pay online).Want to choose your seat? You’ll pay as much as $50 on Spirit and $75 on Allegiant. The newest fee this summer is for printed tickets. Airlines have long charged to print and mail a ticket (up to $65 on some carriers). But Spirit Airlines, which already charges $5 to print your ticket at the counter, will charge $2 for printouts at a kiosk starting June 30. Print your boarding pass before departure. Before your return trip, use the hotel business center. Adding insult to injury, the airlines charge usage fees to book tickets at their Web sites (up to $33.98 round-trip for Spirit and $20 round-trip for Allegiant). You may be able to scratch those charges by booking through a travel site such as Kayak. And unlike other airlines, Spirit and Allegiant don’t charge a fee for buying a ticket at the airport. Bottom line: Before you jump at a discount fare, add up all the extra fees and check fares from other airlines.