Hi Jake.
As far as I know, you can not use one for the other.
I personally had the Columbia dentoform, and was not able to use Kilgore teeth on it.
About online outlets, I do not know of any. However, I think it would be easier (and faster) if you could go down to the nearest dental school (if any) in your area. You should find a dental supply store there. If they are too far away, I would try and give them a call, and see if they would ship the stuff to your address. I don't see why they would mind, especially if you send them a pre-paid package.
Good Luck.