I have a question... If I''m needing a little help with some music for games, how much on average would it cost to hire someone to write music for my game if I had a midi file of the "mood" I would like the piece to sound like?

From personal experience, musicians tend to be more likely than artists to work for free as long as they get credit. If you look around online you should be able to find someone who will either give you a pre-made MIDI they wrote that matches what you need or make a new one.