I'll take your advice guys and search for one in the UK. 
Also, you never said what you use your Amiga for. If it's for games then you'll rarely, if ever, need to go above 640x240 resolution (or the PAL equivalent of the "hi-res" screenmode). In that case, a standard, common 1084 is all you'll really need. I know of only a handful of games (out of thousands) that even require anything higher (like Mechforce, maybe).
Heck, for most action games where there's no fine on-screen text to read, even a SCART connection to a good colour TV or C64 monitor would be quite enough for your needs. You are in the UK, I gather, so most TVs/monitors should have that connector.