I just accidentally bid 25000 on an item that really would have cost me about 10k. It didnt have a buyout so I just bid and took my chance.

I didnt want to bid 25k though. That amount in the box was from a different bid.
There is a Cancel Button in the Bids tab... but I cant cancel because I am the highest bidder.
All other bids on that item are cancelled automatically so a bidder can either be the highest bidder or not in the bid at all. What the hell is the Cancel button for?

I suggest that I could withdraw my bid within 5 minutes of posting, OR the bid amount is set to the lowest possible acceptable amount.

Yeah, this is a bit of a rant, but really, please fix this or give me time to remove my bid.