For a long time my main amp was a NAD 3020i. Finally replaced it with an AVR a couple of years ago, a Yamaha 777 or something, so disappointed at the state of modern AV tech; too complicated, too many issues, it needs updates, etc. The NAD still works fine, but I wanted something with video abilities and 4K support for newer tech (HDTV, 4K later). It doesn't look like anybody makes anything these days that Just Works like the NAD does; the complex functions mean software/firmware is involved, which means bugs, and somehow I don't think sw dev people who work on this stuff have the same degree of design rigour as the hw people.
Likewise, the bluray player I bought way back is overly complicated, trying to be an uber home media centre, etc. Annoys me that it takes to long just to turn the thing on and off. Seems like every device is trying to be everything, which means they end up being not good at anything. I bought my brother a 4K TV and a bluray player, the duplication of functionality between them is crazy. Add to that the mess that is 4K bluray support on PCs, hardly worth bothering with.
As for vintage tech, there's no such thing as objective "market value". An item is only ever worth what someone is willing to pay. Auctions for mint ZX80s (especially unused kits) and Jupiter Ace systems can go for really high amounts (I watched an unused ZX80 kit sell for over 1500 UKP); they're hard to find but highly sought after, so people pay a lot. Is an Enterprise 128 worth 160 UKP? Who knows, but that's what I won one for, because I was willing to pay that much to have one for my permanent collection.
If you want real crazy, remember how much those incrediby rare NES games went for, like $40K or somesuch.
Thing is, the old stuff I have generally still works ok (I have over a hundred Sinclair systems, amazing the printers still work), whereas I fully expect my AVR to just die not that many yeas after the warranty runs out. I started collecting vintage tech because it was rising in value, now accounts for about a 3rd of my storage space, and of course valuable items like the Spectrum 128K don't take up much space, so the value-stored-per-unit-volume is quite good (better than the SGI stuff I normally deal with).
I even bagged a couple of Tatung Einsteins, they still work ok. Lots of Acorn systems, Timex, Commodore, etc. The item that's least likely to still work after all these years though is a joystick. 😀 Most of them were terrible.
Ian.