What Cartridge Manufacturers Will Retip Their Moving Coil Cartridges For A Fee?

It's a matter of semantics. Which is to say that nearly all MC cartridge makers will supply you with a "new" cartridge for a fee that is darn near to the OEM cost of the cartridge.  In some cases, the new cartridge may be your original one that has been truly rebuilt.  In most other cases, the consensus seems to be that the maker simply exchanges your old cartridge for new.  Call it what you will (except in the former case, you get back a cartridge with a used suspension, if that matters).

For the moment... I thought you've missed one letter in your last word. For fee I guess almost all, but for free not to many :-) All you do is to give the core to get $50 for it of the trade-in value and get brand new one for full retail price maybe minus cup-o-coffee discount. The alternative company such as Soundsmith would probably make you wait a couple of months if not longer before your cartridge is back so prepare to get some "loaner" or temporary budget cartridge if you go that way and if they're still around. Everything does seem to be temporary even the members here and even me...

SS do not make MC cartridges, so far as I know.  MI cartridges are easier to retip.