The ‘buyer’s premium’ is normally a percentage additional charge on the ‘hammer price’ of the lot payable by the winning bidder.  It is made by the auctioneer to cover his ‘administrative expenses’.  At a Get Set 2 Move Auction all bidders agree , to appoint an independent lawyer and surveyor.  They provide legal title, building condition and mortgage valuation information equally to all bidders before the start of the auction.  The cost of provision of this information is recovered through a fixed fee buyer’s premium (approx £1,000) payable by the successful bidder, see :- http://en.wikipedia.org/wiki/Buyer’s_Premium