$20 for 100 on ebay. That's 12p a test, cheaper than anything you can find in the UK. I've yet to find anything (other than NFL jerseys) that is cheaper in Europe than in the US.
The trouble is that you need to have an address to ship them to, and a means of collecting them. If you send them through the post you'll get stung for import duty (although it'd still be cheaper than buying them in the UK).
I always come back with my bag stuffed full of A1CNow kits. I'm busy trying to corner the market in ketone test trips (for the precision xtra) to pick up next time I visit.