My guess is that ARP synth you had was an ARP Explorer.
All of my vintage synths were acquired cheap, in the right place at the right time. My Polymoog, Memorymoog, RAM Minimoog, Source, ProSoloist were bought in the 80s-90s when no one wanted analogs. OB-SX and OB-X both were eBay handyman's specials that I restored. Another "right place at the right time" synth was my Moog Taurus I bass pedals.
My FVS was another handyman's special from a studio owner; he got the FVS and a DS-2a sequencer (both with Anvil cases) from a buddy who quit gigging. A repair tech who knew my success with the OB-X gave him my name. The FVS was very dead; I got the audio to work and was able to assess what needed fixing. It was a lot more than he wanted to spend for repair, so he offered to trade it for one of my vintage polysynths. I offered a new polysynth but he insisted on something vintage. I had a 2nd dead Memorymoog and offered to restore that (it would had been a much user friendlier synth for him). For about $600 worth of parts to restore the MM, I got the FVS & DS-2a plus both Anvil cases. Both cases needed re-foaming but it was still a steal.
One restoration pet project on the back burner is my ARP Avatar, which I want to convert into an "poor man's 2600" Odyssey module by installing a MIDI->CV converter and adding extra circuits & I/O jacks.
Pretty cool you have all those vintage synths. Did you get them when they came out? I once had a moog polymoog keyboard. A sequential pro1 and an oberhiem obxa. I even had an arp that was real old not really sure what model it was. It predated the pro soloist. The arp wasn’t much of a synth. It had rocker switches. And a resonance control. It wasn’t an
Arp axxe either. I remember getting it from a guy that had a orginal arp odyssey. The sequential circuits pro1 was my first real synth. The polymoog keyboard wasn’t that good. The oberhiem XA and Sequential Circuits Pro1 were the best out of the three. The obXA was the cheapest . I bought it used. The pro1 if I’m remembering right was $750 new. Strange that the pro1 was more expensive than the oberhiem XA , though it was used. At that time people didn’t want analog they wanted digital synths like the Korg M1 and DX7. If I had kept the OBXA it would have been worth alot today although with the new OBX8 I would think it would be a more viable and cost effective choice. Same situation in regards to the prophet5 rev4 and the Minimoog reissue. Although there are still some people that would opt for the orginal. The orginal prophet 5s
are rare same as the Minimoog modelDI wouldn’t think there would be too many in circulation. Reissues seem like a good option for the most part although the purists may want only the orginal vintage synths.