Well, you can look on ebay or in some internet shops here (like valleyvet.com or jeffesequine.com, I believe they may ship oversees. I know for sure Dover does, but they don't have western bits :) ). Do you want to continue riding western or just because he was trained for the curb? I mean he may do perfectly fine in snaffle if you just want to trail ride him and such.
I compete my horse with the Western Equestrian Societ (www.wes-uk.com)
here in the UK, in a few different disiplins, for which my trainer wants him in the correctional bit to keep him soft as he can be very heavy on the forehand. Only thing is, to compete in that sort of bit I have to go one handed, but so far so good