Mecum Auctions have a Vehicle Sellers Commission ('VSR') of 6% for reserve auctions and 4% for non-reserve auctions at Kissimmee, FL later this month. For the Kansas City (3/11) and Indianapolis Auctions (5/11) the 'VSR' is 7% and 5%, respectively. The Buyer's Premium (commission) is 6% at Kissimmee...not sure if that percentage will remain the same at K.C. and Indy (not available on their website at this time).
http://www.mecum.com/