You may have your heart set on dropping big coin on a bike, but craigslist is loaded with great commuter stock for less than 300 bucks. 90's steel mtn bikes like hard rocks are easily found for 100 bucks, add 300 bucks for gear and you have hours of research and bike part shopping to look forward to. Added bonus: the bike is one of a kind.

If you keep it up for a year, then drop the big bucks.