I have to agree with the others here. Buy used. You'd be amazed at how many Raleighs and Specialized bikes from the 80s and 90s are on Craigslist. No suspension, but you don't need it for a commuter. I'd shoot for under $100. I certainly wouldn't chain a brand spankin' new bike to a bike rack, and what a pain it would be to fold one up everytime you went to class. Maybe invest in a really good lock.