Scavenge, ebay, Sora.
http://cgi.ebay.com/Shimano-Sora-8x3...QQcmdZViewItem
I'm going to take the old mountain bike up to the family cabin, swap it for my old Bianchi Hybrid (622-38) and, depending on the effective top tube measurements, consider throwing a set on there and converting it to a dedicated mud tire/studded tire cross bike for the winter. If it's a flat bar and you set up your bikes anything like I do, you may need to shorten the stem a bit to compensate for the added reach of a drop bar.