They don't really exist, at least not real companies that stock their stuff.
FW doesn't have a distribution/trade program, so a store would pay exactly the same thing that you do to get it here.
By the way, If you're spending $350, you can just spend $50 more, and get free shipping

(
IIRC it kicks in at 200 GBP?)
On the other hand, be aware that I've had a lot of orders screwed up by UPS, and been double-charged for tax -- once though
FW at the point of purchase, and once during customs clearing. I've given up on trying to get my money back.
Now, I keep my orders to as small as possible and just pay the 15% shipping fee. Not only does it mean that I just buy what I want instead of looking for some other thing to add to my order, but also, since it will arrive via Canada Post, it won't have the brokerage fee or double-tax.