Ed Brown, Chip McCormick, Wilson combat, Kimber even sells parts. Not sure why you would want a frame unless your wanting to go to a double stack. Caspian is the only ones I can think of that makes frames off the top of my head, I believe they also have some parts too.
BTW, I believe if you go to a polymer frame you will have to use a ramped or para-ordnance type barrel, I don't think a reg colt 1911 barrel will work. I could be wrong though, have been before.