I'll chime in.
I mostly agree, used gear can be a great market, but it isn't the market for noobs. If you are new to this hobby, or buying anything on the used market, then it's best to proceed with caution!
And, I agree with TLS. If you are gonna buy used, then that next insurance policy is to be able to troubleshoot and repair your own gear. If repairs after purchase eat up my savings, then I'll just buy new and be done with it.
It's absolutely worth the time and $ to invest in some decent testing gear and learn how to use it. I got all my electronics gear used too! And it all works great!
A bench power supply = $60
A BK precision function generator = $50
A 100MHz Tektronix scope with 2 brand new Tektronix probes = $300!!!
That was just about a steal on that o-scope. So, at just over $400, I have most of the gear that I need for long-term electronics work. The time to learn these skills....well, there is no substitute for experience and I keep on learning more every day.