The other important point to note is that supply of these parts is now severely constrained. These components, once plentiful and sometimes inexpensive, have gone through approximately 2 decades of attrition, by means of failure or disposal. The remaining parts are more and more likely to be in the hands of people who know both what they are, and what their "value" is. Not everything will remain functional, and most will never see another release. Although several clones are being produced by the community, which really is astonishing. ARGUS, Keropi's MPU-401AT replacement, SIMMCONN Revival, and the Dreamblaster are all marvelous projects, which show just how committed this community is.
I was pretty young during the DOS phase, being a VERY late 80's baby. Consequently, I did not know what was good and bad. Setting up Duke3D was a frustrating affair because 5 year old me did not know what kind of sound cards existed, let alone what IRQ and DMA were. The list of options for sound cards was not something that I could use to determine which one was better than the other, and all I knew was "Sound Blaster or Compatible".
I never left the world of computing, but my interests changed with time. Finally, a friend of mine gave me an old school PC (it literally was an old Pentium MMX from a school!), I used an AWE64 Gold and Rage II+DVD that I had found at work, installed them, and used it to play some games. 20 year old me was able to look through the list and wonder what the options were, then Google them to find out. That allowed me to use my modern knowledge of hardware and software to learn about the past options, which then, as most here will understand, fostered the urge to have the best. I suspect that, as others have pointed out, people who used to have middle of the road systems are revisiting things and want the best experience possible. This has created a larger demand than would be expected.
I expect that the MPU-401 craze is due to an aversion to emulation, which most here have, coupled with the collection instinct and prestige which come with owning rare hardware. This also eliminates one of the (many) big drawbacks of Sound Blaster cards.
I agree that prices will likely remain high, although some speculation is certainly occurring. Supply and demand are working actively here. Demand is certainly going up by the number of introductions here and on Facebook. Supply is most assuredly going down as well-to-do collectors sink their teeth into the remaining stock.
MT-32 Old, CM-32L, CM-500, SC-55mkII, SC-88Pro, SC-D70, FB-01, MU2000EX
K6-III+/450/GA-5AX/G400 Max/Voodoo2 SLI/CT1750/MPU-401AT/Audigy 2ZS
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