If OP is truly (truly) a rare cave collector there is a holy
grail €10,000 program development board of SDOJ that cave accidentally released into the wild that is missing from that collection too

.
The saddest thing is that the market for these boards will (eventually) disappear in the future along with the generation that would most likely play them. Many of them will fail In the interim period in any case having not spent much time being played or even in a cabinet generally (the later cave games are notorious for failing). I bet some have spent more time in the custody of one or other postal services than they have actually spent even out of their boxes.
I’m sure there are many who have been here longer than me and who have probably owned some of these in the past that would probably like to still own them. Not because of what they are now worth but because there is no way for the average person to be able to play any original cave game now and as a consequence many other shmup titles that are good in there own rights but have been snapped up around the hype.
I started out very late in this hobby and spent the last two years in complete disbelief of how much it changed from when I first looked into it 12 years ago and the continued sharp upward trend over the last couple considering there is supposed to be less money floating around. But I made some friends and got over it.
I’m happy to say that I can play almost all of these games save for the low number exclusive collector only runs on some very affordable kit which will eventually go into my cab. Having been very patient I eventually managed to obtain one original Cave game for a very reasonable price that now sits in my cab for me to play (when life allows).
As the cave games are now being re-ported to the latest consoles I’ll get the chance to get some of the newer versions with the improvements and/or any new modes.
Authentic slowdown is overhyped for the prices these fragile ‘investments’ now command imo (I’m not playing them to chase record scores in any case).
Better of investing in something inert and not a niche market item that could very likely end up worthless. Maybe erm…. Let me think…. gold or platinum at least it looks nicer on a shelf (shiny!). Then whilst that is sitting there looking pretty and slowly appreciating in value on the shelf you can spend some time playing the games instead of worrying about your investment.
TLDR unless you are an investor or score chaser there are better things to do with your money imho, but each to their own……..
………There’s a Pony III or an Egret II (possibly 3 if you are lucky) listed elsewhere you can treat yourself to instead. A much more reasonable Investment get one before they are snapped up
