sold a transmission now having buyer problems

I gotta go with 120 being a good core price. It's not that expensive to have it rebuilt. I'ld say the tranny shop screwed the pooch by not going thru it. It is kinda telling that the guy was looking to buy a working trans for a C note. The trans didn't fail expectations, the tranny shop did.

That being said.....
What's peace of mind worth? Maybe split the deal and give the dude 60 back after reminding him of all of the above? Maybe give him the whole thing back to just disappear of the face of your earth? Kinda depends on if the dude is being a jerk about it. You've gone a long way on your word in dealing with this thing.