From the T & C of my local auction house:-
All charges are subject to VAT at the current rate with specific exceptions.
Vendors Terms and Conditions of Sale.
1. Commission is charged at the rate of 20% on the hammer price of each Lot with a minimum charge of £3.50 per Lot whether sold or not. Lots selling for £23.50 or less, or unsold against a reserve will attract a charge of £3.50
Buyer Terms and Conditions of Purchase
1. The Purchaser to be the highest bidder who will pay the hammer price plus a premium of 20% plus the current rate of VAT thereon.
So 10% to E bay is quite cheap in comparison …