Have you looked on petfinder? -
http://www.petfinder.com/search/search.cgi?breed=rat&tmpl=&preview=&animal=Small%26Furry&preview=&zip=TX Might be worth checking there if you're open to rescuing rats.
There are some breeders in TX
here too, if you haven't already looked there. They might be nowhere near you though - I have no idea with being in the UK myself lol.
I've heard that forums such as Goosemoose and The Rat Shak tend to have rats looking for homes in various areas too, so it might worth checking those out.