It is not really to do with the Shop it self, but the item, you will have to pay VAT on items imported if above £18.
Some ebay sellers may be prepared to 'mark down' a value to below that threshold, or declare it a 'gift' which should help avoid charges, WindyCityWholesale would be an example. I am sure there are other sellers who will assist but many will declare the full value as it is obviosuly tied into the amount the package is insured for.
However, Customs over here are free to check an item out and if they believe it has been falsely declared you will still have to pay, or possibly lose the item (I think).
For the most part the Charges are paid on arrival but somewhere like FansEdge or Amazon.com you can pay all taxes in advance which can save a few pound as you avoid any 'Handling' charge by the delivery company.
Unfortunately if you are importing Customs is just one of things you will have to accept, last week I had to pay £19 to release my Lawrence Taylor M&N jersey (£11 VAT and £8 handling) which I wasnt happy about, but once I got the Jersey, all was forgotten