In a Badger land, which is probably not dissimilar from a big ten university town known for welcoming a certain former NFL coach to its football facility, $500 is probably 2X the money to find and convert a MTB or hybrid into an effective commuter. Then you can keep your GF for it's intended use. I've got about $160-$175 invested in the Miyata below, which I frequently refer to as the poor man's Surly LHT. Since the photo, it has had a rear Blackburn installed.