Re: Bench fee at local guitar shop.
One of the benefits I get for buying through my local music store (and often they will price match SW or MF) is free tech support. Guitar adjustments, amp repairs, pedal repairs, and lots of advice. I still usually bring in a bottle of good scotch or bourbon for my tech to enjoy. One of his students works for Taylor now so I know I am in good hands. I did have him rebuild a bass (new pickups, pots, wiring, shielding, the works) and I paid for all the parts and he charged me $65 bucks labor....cannot beat that, plus a good bottle of course. The only time I buy elsewhere is on here or new if they cannot get it.
$To the OP..... $50 bucks sounds cheap to diagnose an issue with an amp.....if he is a stranger and you have no relationship. If you do your major business there, it should be gratis and then charge for the repair.
Brad