Why the difference in resale value?


The Adcom GFA-555 and the Onkyo Integra M-504.  Two relatively close-in-price power amplifiers that emerged in the mid 80's to critical acclaim from the audio press. The asking price for the used Onkyo on sites like ebay is frequently higher than its original MSRP; for the Adcom, not nearly as often.  Why is that?  
rwp2694u
Probably just supply. Why would anyone actually care?

"Actually" ?

Let me help. Because this is a friendly discussion forum where the bar to ask a question is reasonably modest?
Well since the market sets the price, the comment "opportunistic sellers" is just plain silly. Obviously demand for one is greater than the other. Number of units produced could have some bearing.
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  If I were in the market for such a product, and the price seemed high, then I would want to know if the product had been reconditioned, restored, upgraded or whatever.