what is this worth?

You have the time - email the seller and talk him through "or want me to try some functionality tests with it I will happily oblige" - such as getting a couple of traces up and see if they vary when the probe is touched.

My normal reaction to anything auctioned as "untested" is "unworking". However, it is just about believable, based on what the guy buys and sells, that he can't use a scope. You would know better than I whether he is likley to have used a scope during his school years...in the USA.

As to how much use a 60MHz uncalibrated scope is going to be to you, only you can answer. For me, it would only use up valuable bench space. I am a great believer in buying good quality tools, then looking after them (and never lending them...) ;)

It depends, if you know how to use a scope and this one works and has the needed bandwidth then I would say yes.

Most any general purpose scope will do for basic audio repair.