I dont't think that the FT-950 is a 20+ y old radio. I believe it came out in 2008 or 2009.
I bought mine used in 2011, and I am still very fond of it. I missed the opportunity to buy the AC0C roofing filter, but alternatives have been published. The IF I/O allows for easy addition of a preselector, something you would have a hard time doing with more modern radios. The connectivity is great, the construction is solid, the radio is easy to service, and it's a beauty. I say $600 is a fair deal for the radio, if it's in good condition.