Be certain that if you purchase a TC frizzen you get the new version. The old style are case hardened and it is likely that once that hardening is worn away you will will be looking for another. The new version will be jet black and hardened through. The Gun Works may have both. Specify new version when ordering or you may have a chance at getting the old. By the way, I believe their current price is around $30 which is considerably less than an L & R replacement lock.
As stated above RMC Oxyoke is a good source for the Lyman replacement frizzens altered to fit TC locks. Several years ago I purchased 2 spares for my rifles because at the time I was unable to find TC frizzens. I believe the price was about the same. They are still in their packages as I haven't had to replace either yet.
Good Luck,
Ed