I'll be shooting for the compo if I participate this round, but normally I do the jam. As such, a link I highly suggest to anyone participating in the jam is Makerbook.

http://makerbook.net/

These are mostly free, royalty free, and often licensed for commercial use as well. So if you need some additional assets in a pinch, worth checking out, as there are resources for every asset type you can imagine. Sound, sprites, photography, music, etc.

Just remember, if you use a lot of them, you should probably opt out of the relevant voting categories; not your assets, not fair to have people voting for that category in your game. We're voting on your efforts, not your search engine proficiency.

Still, having sound in your game is better than none at all, and can help boost your rating in the other categories. Using stock sounds might take you out of the running for the Sound voting category... but how you use it might get you bonus points in Innovation or Fun. Get creative!