Phew! I just really love to see more games like this, no giant budget or unrealistic expectations. A game made by a person who loves games. No strings attached. And I'd love to see it grow. Still, if you're interested, I suggest you look into some royalty free music and assets.
Try using sites like [DOVA SYNDROME, M-Art, Musmus by Watson, Maou Damashii, and FreeMusicArchive.
You can also get access to free custom graphics via artists like Starbird and their free tilesets!