There's preparing yourself for a career fair (which I would characterize as having a fairly specific "hit list" of companies to speak to and topics to talk to them about) and then there's wearing a suit (spending at least $100 on a rarely-worn garment on a college student's budget). One of these is a much more meaningful activity than the other. And given the culture of technology companies and the high demand for developers, you want to limit who's going to take you seriously.