RushJet1 remade GB MMII and III to not sound like garbage and did some incredible VRC6 versions of the NES games. His Bandcamp downloads even include the .nsf so you can play the games with them. Seems like you can get them on CD if you want.
Some choice tracks:
Heat Man,
Top Man
Oh and you may wanna grab the 2002 Rockman 1-6 set since that's the only one where MM1 and MM2 aren't messed up from what I've read.