A method of allowing a seller in a multi-unit auction facility to offer buyers the option of buying an offering at a pre-auction seller determined price or using a regular auction process. In one embodiment, the option to buy at the pre-auction seller determined price remains throughout the auction as long as there are units of an item remaining that have not yet been bid on. In another embodiment, the duration of an option of purchasing an item at a pre-auction seller determined prices depends on a configurable threshold, the current auction price in relation to the threshold, and whether the unit has been bid on. In another embodiment, a participant in an auction is allowed to re-bid, but is not allowed to reduce the price in that re-bid, or the quantity in that re-bid, unless that participant is currently not winning any units. In yet another embodiment, purchases during an auction at the pre-auction determined price reduces the quantity of that bidder's previous bid (if there is one), and reduces the quantity available for bid for any later bidders (but does not reduce the quantity of any other bidders who bid before the fixed-price purchase).