try here mate:
http://www.ractyres.co.uk/
depends on the tread pattern you want, but you might get a good deal - if you choose the fully fitted etc. option, you can have a look to see if there's somebody you would trust to fit them (down this neck of the woods, Jim Dixon in Cumbernauld appear to be on the fitting list and they get a good reputation and are well recommended by a lot of people on here)