A convenience fee of $11.50 per traveling customer will be applied when booked on allegiantair.com or through an Allegiant Air call center. Travel purchased through Allegiant Air call centers will cost an additional $10.00 per segment.

and also

For the convenience of using any of Allegiant Air’s booking services (inclusive of call center) there is a fee of $11.50 per traveling customer. Purchases made at any of Allegiant Air’s Airport Ticket Offices will not incur a Convenience Fee of $11.50 per customer. All fares are subject to change until confirmed and purchased.

They do allow for no-fee booking at the airports, so I guess that gets them past the FTC, though the online booking fee can’t be seen as anything more than a cash grab from any reasonable point of view.

Just another reason to not fly those carriers…

I think you should also push them to drop that fee…because while there was ZERO chance I would ever fly Spirit, I do enjoy taking Allegiant to Vegas every now and again from my small town!