Wow, everything posted for sale is ''light use''??

I guess as they say "you don't have to eat the whole egg to know it is rotten"

sell it and move on...

I'm sort of an audio hoarder. I have stuff sitting in the closet for years. Stuff like cartridges, amps, preamps. Even some of it in sealed (NOS) boxes. Some of it does only have a couple of hours, from trying it out. A lot of NOS spare tubes. The stuff I use every day is another story. High hours that are unmeasured. There are ads I've seen where the people must not be audio people. Auction resellers I'm guessing. The description they use just doesn't fit. Those ads make me curious at times. Ads for CD players that say low hours, but a tired (dim) fluorescent display says a lot there. The stuff here looks a lot better at times, than some Fleabay ads. Use your better judgment.
The ads with the high prices that just sit there are another one I can't figure out. I thought they want to sell something, but they won't adjust their prices into reality.

I have seen some beautiful, immaculate amps that I would like to have, esp the Japanese ones with the big meters, but when you click on 'research this item' they are sometimes as much as 25 years old. What are the major considerations in evaluating old equipment and what is considered a good price vs the original MSRP.

"The ads with the high prices that just sit there are another one I can't figure out. I thought they want to sell something, but they won't adjust their prices into reality."

In that case they are clearly fishing for suckers. They want to sell but only if it translates to a big payday and are willing to wait.

"What are the major considerations in evaluating old equipment and what is considered a good price vs the original MSRP."

The same as any other except issues are more likely with older gear so assume that by default until you are able to disprove. Not a bad rule in general.....

Original msrps from years ago are not really that meaningful for determining current value I would say. You have to look at current market prices and establish the true condition of the gear in question, again probably always a best practice regardless when buying.