I got my shoes reheeled for the first time ever. 1890yen. One web site recommended attaching a thin sole - it apparently doubles the life of the shoe. Aside from the heel, the sole of my shoe is holding up very well though, so I don't think I need it.
I'm now shopping for a set of shoe trees (I only have one pair of shoes that might actually benefit from it), leather cleaner, leather conditioner, and waterproofer. I have a bottle somewhere in MD or CA, but I won't be finding it anytime soon.
I bet my mother never conditioned her leather couch. Funny how nice things require maintenance. I don't think she ever polished the wood furniture either. I polished it once, but after 20 years of no care, I don't know how much of a difference it makes.