Defunct Company Gear Value

Rrog, I got the $6000 list price from a 1986 Stereophile review. Perhaps the price went up and was $8500 when the model was discontinued. Still, even 37% is pretty good for a 20+ year old amp from a company that no longer exist. I paid around 22% for a 19 year old amp from a company that still does exist.

It clearly depends on the company. . . although it may be different between electronics and speakers. Just look at the price of a pair of Rogers LS3/5a.

The aforementioned Dunlavy and Threshold might be a bit unique in that besides having technical and sonic prowess that still compete with more modern offerings, they also have some type of support available.
The Threshold gear still has support through Nelson Pass' recommended ex Threshold tech Jon Soderberg of vintageamprepair.net as well as advice from Mr. Pass himself on diyaudio.com.
The Dunlavy's used mostly off the shelf parts, that for the most part are still readily available.

Unsound, You are absolutely correct regarding Threshold values. Once folks became aware of Soderberg and Pass Labs started up Threshold values immediately started to climb. However, I believe Dunlavy speaker values are strictly based on performance.

Good example of prices dropping after a Co. goes out of business are the Hales speakers that I used to own...Paul Hales closes up shop and the next day the speakers dropped in value by at least 70%! Same for numerous cable manufacturers that have gone out of business. Highwire cables come to mind. Highwire closes up shop and "voila" values drop like a stone! Plus, the other issue is that now nobody has heard of the Company, leading to even more depreciation....IMHO, the moral of the story should be to buy ONLY gear from a larger well known vendor, IF you are concerned about re-sale value.