firstly get a new repair guy this person is trying to pull a real fast one on u. the issues u having with fish tales aint that hard to fix and wont cost a fortune surely. infact he should pay u money in this trade i would say.

if u do a pricecheck search u will see that lah is probably at the most a $1300 pin and thats someone winning one on ebay. i would say maybe $1100 for one would be fair.
fish tales is a $2000 game.
so if anyone should pay the $900 it should be this repair guy, i would understand if he maybe said a straight swap but that deal with paying money in well thats just silly.