THe only alternative I know, Ten Tec sells their variable caps and
variable inductors that they use in their tuner as open stock items.

MFJ will sell the roller inductor they use in their tuners. I bought one at
the MFJ exhibit at a hamfest. They indicated that they will sell pretty much
any part of their products if you call and let them know what you want. I
built my tuner out of the MFJ inductor and Ten Tec capacitors. It's my MFJ Tec
tuner. Parts cost around $150, works well and has handled the legal limit.
73 Gary N4AST