Wow! Pretty neat! I'm looking forward to seeing the pictures! BTW, I bet them Saturn cartridges are VERY expensive....
Hell no! MAK Japan in Tokyo was selling packs of 4 for 550 yen, I got one but I really should've gotten all of them. Those were the common games though (baku baku, VF kids, Winter Heat, etc.). Shmups were in the 5000-10000 yen range (make that $60-$250 in the West :-( ), but Radiant is cheaper than the Saturn version if you look good :smt043
Standard goes back to 1988 or so I think. But remember, the Jamma spec only allows for 2 players with 3 buttons and mono audio, thus MOST "Jamma" games are "Jamma+" which have the normal Jamma connector and aux connectors for additional buttons and a right speaker.
Yeah, its easier to run RGBScart from a Supergun. If you want S-Video you're gonna need a J-Rok video encoder. And that costs, plus you need to wire the damn thing in.