Agreed, eBay and Paypal combined normally take around 13-14% off the final value, although they do charge an insertion fee if you set a reserve, or a pre-determined sale price. I sell on eBay all the time, overall it's a decent way to get your stuff in front of many people.
My wife works at an auction in Horsham, has done for over 30 years, it's a simple process to sell, and buy. You are always made aware of the rates before you buy or sell and should factor this into your budget. The benefit of using such a place is that they do promote your item locally...