Your margin is a priority if you want to make a profit. If Airbnb or FlipKey charged a 3% fee
on a single listing for daily rent, it likely wouldn't bother you much.
However, if you lease an apartment or flat for three to six months, the fee is going to be a considerable amount that you will have to pay the platform. In the case of VRBO, it will cost you $349 annually
to advertise your property, though they do not charge you anything per booking. In any case, even if you believe you can bare these expenses for their services, renters have to pay even more (up to 20%
on AirBnB) to the platform.