Well, you already made a commitment to buy something. Like notladstyle said, now they will have to still pay all those fees and such, so they get screwed out of a sell being on Ebay plus the actual "profit" they should be getting from you beacause of the purchase you made. It would be different if it was a clubgp ad or something because they could just re-list it (without paying a fee) or take next person in line. Instead they are going to lose money regardless because it's an auction.
And like Palsut said, why don't you send them an email and see what they have to say about it.
I understand, "your shopping around", but you made a decision to buy something already. Man up and pay for what you purchased.