The present invention provides a computerized system and methods for conducting on-line auctions. One or more concurrent auctions for one or more lots of products or services may be conducted. A dynamic pricing mechanism allows bidders to view the price at which a lot is offered and to make a bid when the price is acceptable to the bidder. In some embodiments, the results of the auction of one lot affect the starting price, reserve price and other characteristics of auctions for subsequent lots. In some embodiments, the pricing of a lot may depend more generally on the demand for similar products. Multiple stage auctions with declining price and rising price aspects are also provided.