This was played on the Kega Fusion emulator last night. Didn't feel like setting up a Genesis system and wanted a little Sonic 1 playtime before shutting down my PC.
The original Sonic The Hedgehog on the Genesis is one of my Top 5 video games of all time to this day and I have the original cart with along with the system in its box from Dec. '92 (bought from Electronics Boutique for $119.95).
As for MUSHA (also among my Top 5 video games), I owned two original copies complete in box and sold them for a few hundred $ each probably around 10 years ago.
I got very lucky acquiring one copy as I bought a Genesis system (complete in box) with a dozen or so games all complete in box and MUSHA and Mega Turrican were included.
I paid around $100 for it all from a local guy who was moving and he posted it on Craigslist.
That was a very rare stroke of luck because that haul would easily go for a good $700 today, if not much higher.
I do, however, own a Repro copy of MUSHA with its box, manual, and extras that I bought about five years ago from a guy who was doing high-quality reproductions of Genesis games using the standard ROM boards, not the Chinese-junk thicker boards that can damage the cartridge slot and as far as i'm concerned it's as good in every way as the original MUSHA cart. I paid something like $20 for it. Here's a few pics of it...