I did same, once, on a visit to parents (who lived in Switzerland at the time). I stopped en route and had all four tyres on my Camaro replaced and saved about 400 quid.
I recently sent 4 Goodyear Eagle F1 EMT's over to England for a friend, who runs a (dare I say it) C5 - and even including shipping (UPS) and duty, saved 150 pounds per corner.
I've also just re-booted my car with Eagle F1 GS D3's - which are absolutely fantastic tyres, at a cost of $950 (about 425 quid). I believe they cost 375 pounds each in England!
Send me your orders!!!