I have quite a few vintage or old amps that I use every day. In my living room system I have a Thredhold S200 class A amp running through an Audio Resesrch SP1 preamp into Wilson Watt/ Puppies.
The Threshold I got was a one owner who had it serviced before I bought it, new caps,etc.. It works and sound very nice. I also have a Krell KSA 150 which I bought after it was serviced by the previous owner. It’s my main amp in my dedicated system and I will never part with it.
Some older gear is just as nice sounding as newer stuff, maybe not as low a noise floor and the cosmetics might not be up to snuff for the wife but I wholeheartedly believe you can get some excellent equipment at good prices that will last another 20 years.
Then at that age they probably would be collector items and fetch a good price on the market. Don’t be afraid to take the plunge and buy vintage gear if it’s been properly maintained. I haven’t regretted one purchase yet and I have a ton of vintage gear.