I've used them before, through their ebay shop i believe. Cracking deal but we did get stung for customs charges. After they were paid we still saved a stack.
used them a couple of times - no problems. Got customs fees once - photographed the invoice to them and then they credited my account with the amount I got hit for.
I've used them before and I will again. If you want to avoid VAT, then look at the ads (on ebay). They will clearly state if they will refund the tax or not.