On flights, it used to be that carry-on luggage was as free as a complimentary bag of peanuts, but that's all starting to change. In fact, a third small airline just added a fee for passengers who wish to bring a carry-on bag.

The carrier, Wizz Air, is based at London's Luton Airport and allows only one piece of luggage that's able to fit under the seat in front of you. As of October 24, anything larger than that will cost about $13, provided the luggage fits in an overhead compartment and that passengers can stow it without assistance.

According to the airline's website, the fee is meant to "encourage passengers to bring smaller baggage onboard and make the boarding process smoother and faster."

Wizz Air, which flies from London to central and Eastern Europe, now joins U.S.-based Spirit Airlines, which charges as much as $100 for carry-on luggage each way, and the Las Vegas-based carrier Allegiant Airlines, which charges anywhere from $10-$30 for carry-on luggage.

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