Two things that always help brighten my mood when I'm low are exercise, which is cheap. Walking doesn't cost a thing and it really does make a difference. The second is getting out and volunteering. That inevitably helps me with perspective and shows me that I don't have it so bad. Also try journaling, chatting, and/or blogging to take care of the urge to talk about politics and religion.

Times are hard right now for an awful lot of people. Sounds like you have a home/family and a fiancée and are making forward progress in college. That's pretty darn good, considering the alternatives!