$200 isn't a deal but it's okay I guess. I'm sure they sell for a lot less than that if you have a little patience. If you are only looking on ebay then you might always have to pay that. Like I said, I passed on the whole game for $100. There is no shortage of PO parts, they just haven't become popular enough for people to dig them out of their storage bins. If tomorrow, PO took a huge jump in interest, you'd find dozens of kits on ebay.
Did those games have Sanyos in them originally? If so, that is probably what most of them have in them now. It would be pretty relevant, esp. if you want to start with an original cabinet.
I don't know about the Arm Wrestling controls, can't help you there, but I was thinking about 2 or 3 games in one cabinet. It can be wired easily and only require a 3-way switch, or perhaps a 4-way switch (hard to find I'm sure, but I'm also sure they are out there). If you look at it like that, you could have a PO/SPO in one cabinet for close to the cost of the game (Say, $400 for the game and another $100 for the extra board). Simple...
With the PC hardware thing. You are talking about using a specific video card, presumably with Windows, plus the help of some oddball software. You would need ALL of these parts to continue working. I don't think Windows is very future proof at all, in fact I'm fully expecting newer versions of Windows to "expire" at some point. Many pieces of hardware made for Windows will need special drivers to make it work correctly, often which don't work with future Windows versions.
I am probably biased, because I have been dealing with some obsolete systems for years, and it is a challenge to keep them running.
Anyway, I'm not trying to argue this, because obviously it is a matter of opinion. Especially the future-proof thing, which we could debate forever.
I'm just saying that you can have what you want (2-in-1 PO/SPO, possible another game or two), for not much trouble or money ($500?), and skip the whole MAME thing. IMO, that would be the way to go.
Wade