I might have a used set of pedals in your budget..lol, but in all seriousness.
Keep an eye on this bike. CT drops this bike a couple times a year to half price. so about 180 bucks.
http://www.canadiantire.ca/AST/brows....jsp?locale=en
A guy at work has ridden one of these 5km each way for 2 years with little maintenance. And it is not something that is gonna be stealy. If you are commuting, don't buy a mountain bike, get something built for road. At least that is my opinion on it.