GB has instructions for what to do with a nonpaying bidder. Basicly, you give him bad feedback & GB credits you for the selling fees. I've had winning bidders offer to reimburse me for the fees, in which case I don't report them to GB, just relist the item.
GB doesn't have the "second chance" option that epay has. I'm not even sure that you can contact other bidders if they haven't contacted you first.