good to hear you want to make free games, that's very admirable work! i think people are too quick to try to capitalize on any modicum of talent they have, and in the process cheapen it. once you dedicate yourself to selling your skills you make your life a business, rather than a life. sharing is an important skill, one that doesn't get enough credit.
you can use bfxr to make 8 & 16 bit sfx easily. also the newgrounds.com music community has tons of free music (and hidden talent) for non-commercial/attribution license. since you make good free games i'm sure you could even find somebody on there to make original music for you.
oh, and opengameart.org has lots of free everythings! check it out if you haven't.