There was a guy called "gunman63" on ebay from Michigan. I bought a lot of original quality T parts from him. I don't think he's sells on there now. But it doesn't hurt to look.
There is also a guy in Canada who is on ebay and deals with original T parts. I think he's out of Manitoba. I've also bought a few quality parts from him.
Other then that, all I can say is to try, 09-40 on ebay, Lang's, MAC's, Snyder's.
It depends on what you're looking for.