Here's the story.
So, I went on ebay to look for a DS and had set a maximum bid of 55 dollars. The next day I look at the amount and it was around $75 with me at the leader. I looked at my maximum bid(which had doubled) and emailed ebay asking them to retract my bids, but since the auction was ending in less than 10 hours, I couldn't retract the bid and the seller wouldn't cancel the bid.
I ended up winning at 91 bucks...ugh.
[EDIT]
It's also happened to someone else i knew, who bought a lot of 25 used 360 games, set a max bid of like 30 bucks and they increased his max bid to like 350 dollars. :\
Rule of Thumb: Use Gamestop and not
Just get one at regular price.