I had a very eye-opening experience on eBay once....

I learned not to use eBay when coming home at 8 a.m. after working all night and being half asleep. The Buy-It-Now button and the Bid Now button can look awfully similiar. The "Congradulations! You have won the auction!" part reallllllly woke me up fast, since it was for a Porsche convertible.