It seems to be a bit of an odd contest, with six pieces of music being requested. Either one person would have to do all 6, or you'd have to choose songs from multiple people. It just seems a bit disorganized, especially if you have to give prizes to multiple people. Also, people won't be inclined to make 6 pieces of music.
I wouldn't really worry about music until you've gotten a little farther on the game. It's looking really nice. Then advertise here or on Gamedev.net and get yourself a composer to do your music.
I'd just stick with the placeholder music for now. But, if you continue this, I hope you get tons of entries
Come see the WIP!