Good post. Also has to be remembered that some of the oldies in good nick are in that condition because the original owners and beyond found that weren't actually that good...the best ones got gigged into the ground! I had a '68 Jazz that looked fabulous, but was an utter dog. And a '69 Telecaster Bass that looked an utter dog, but was fabulous!
Every bit as much a lottery as buying a new bass. Certainly not remotely worth it JUST because of what they are. If they are good, fine. If not, then they are very collectable firewood, or good only for vintage spares.