Auctions consist of bid price, buyers premium and sales tax. The buyers premium is a fee added to each idea a bidder wins. Buyers premiums range anywhere from 15% up to 20% and higher. The buyers premium is also known as BP. For example a bidder wins the bid on a shop machine at $720.00. The BP is 15% which is $108.00 totaling to $828.00. Sales tax also would be added bringing the final total to whatever the sales tax rate would be at that auction site.