I think that the McIntosh 2300pre is the single HIFI product with the highest used price. Most used items a quickly down to 50 or even 40% of new price. 2300 is sold for 60 or even 70% and they get sold! I found out this by myself looking for this pre here in Europe. There is allot of "cheap" used Mac power amps but hardly any preamps especially not 2300.
I know there is a "cult" for MacIntosh tube equipment in China (I think also in other Asian countries). I was in a high end mall in Shenzhen a few years ago and there were several shops with MacIntosh tube amps selling for very high prices. One of the shops had the giant Mbl Radialstrahler 101 (sp?), used also in their display window. IIRC, some old Marantz's, again tube as I remember, were selling for high prices.