Disappointed first time buyer

I part took in an online daily auction a few days ago, and the price was bumped up to 26000, from 11 000 for a damaged car. I felt that the price was ridiculous and requested a return of my deposit. They're telling me that they'll have to deduct 10% for cancelation, and that amounts to 2600 out of 5000? How is that fair? This is my first time doing business with them, I wasn't even aware of such information.