I would argue that $180 for a used watch is not cheap. It may be far less than a genuine daytona, but it is still a fair amount of money to spend.
What you are suggesting is that the buyer (who bought a watch advertised as working) spend an additional $50 on tools, so that he can attempt to fix a watch(with no experience) that he was told was in working order. What you consider easy, others may find difficult.
He payed for a working watch, he should get a working watch. If he had bought a watch that was advertised as needing a minor repair, he would be responsible for fixing it.
I do not think it is unrealistic to expect a working watch, when you are told you are buying a working watch. He is not complaining about a scratch or the lume not being bright enough, he is complaining about receiving a watch that is not working(that was advertised as working).
I think the seller will make it right.
Robert