Brings up an interesting question (for me, anyway)- how worn can a fretless fingerboard get? So much that there are noticeable grooves under the strings? I imagine it wouldn't be too difficult to sand it down a bit and refinish. I have a fretless, but I've used only flatwounds. I've never noticed any wear. Maybe I need to play more...
http://newyork.craigslist.org/mnh/msg/964691560.html (http://newyork.craigslist.org/mnh/msg/964691560.html)
That's probably the one that's also on TalkBass. It was listed there as defretted as well, so a good price if you can accept that it is a well-played bass that isn't factory fretless.