Allow any seller to close auctions early providing that no bids have been placed. Could be a duplicate, item could have been broken, lost or stolen, sold at car boot (I've done that once ops: )
At moment until buyers increase, one bid is normally enough to win most auctions.
If a seller wants to close an auction early when bids have been placed, then what about a email request goes from seller to buyer (automatically by Ebid) with reason for early closure (item broken etc). If buyer agrees auction can be cancelled, if not the auction runs, leaving the buyer the opportunity to leave relevant feedback, if they think the seller is telling porkie pies.
Also, perhaps come kind of counter system for sellers who are are trying to close auctions early with bids on them.