Well, my one is shot to pieces. A new one from Lexus UK is (wait for it)...£550!
Even if I get a new one from Lexus USA, price including shipping and duty is £370.
Luckily, I've managed to get hold of a brand new one which is basically a pattern part. A price of £234.
Once I get the details of who makes it, I will post on here, such that other owners know what to do if they ever need a new rad!