I just bought a Kona Paddywagon. Flip-flop hub so you can try riding fixie or SS, fender mounts (and clearance), and ~$600. I plan to use this as my rain bike this winter. So far, totally happy with it.

A note on SS: I've got some hills (mostly small rollers, 15 miles each way) on the way out to work and I've been surprised how much the SS works my legs just making it up these hills! Be prepared when you start riding it to have some leg fatigue. I'm alternating between the SS and my road bike to give my quads some rest while my legs adapt.