(CNN) - Hold on to your seats for this story!
Airline travelers are just getting used to paying for checking their luggage.
Now an airline has taken things a step further, and will begin charging for carry-ons.
Spirit Airlines says it will charge 20 to 45 dollars for overhead bin items.
The cost depends on whether passengers are members of Spirit's ultra-low fare club -- and whether they "pre-reserve" their carry-on bag in advance.
Passengers will still be able to bring a personal item that fits under a seat for free, such as a purse or briefcase.
The new fee is effective for reservations made after April 5-th for travel starting August 1-st.