I'm pretty sure the ebay "contract" is between the 
seller and high bidder at the close of auction--you're
not obligated to buy from anyone if you weren't the
high bidder when the auction closed...
anyway, they can't file feedback on you since you
weren't the high bidder, and there's
no way they could file any fraud charges, so even suggesting
that you're obligated to buy it is ridiculous!

sometimes it's a nice suprise~depends on if they were
left breathing a sigh of relief that they didn't win
the cel for that much ;)  I've had plenty of auctions
that I was pretty happy I lost after seeing how high
I'd bid.
rosemary