troll garage sales and dump days. 10 speed for like 10 dollars.
if you have experience wheelbuilding you could rebuild a formula hub into a rim with probably even the same spokes and nipples for true cheapassery (relace 2x if too short, put twists in if too long etc) that's a bad idea, but cheap.
if you can't just buy this rear wheel:
http://bikeisland.com/cgi-bin/BKTK_S...ls&ProdID=1639
though wheel sizes won't match (front will likely be a larger 27"). if you want them to match pay a hundred for for one of the other ones there (with 120 rear spacing).
maybe 40 bucks for tires and tubes from performance. also a 3/32 cog and lockring, that's like 25? so maybe 170 for a conversion.
might as well go with something like this:
http://cgi.ebay.com/NEW-ROAD-BICYCLE...d=p3286.c0.m14
and use ebay bucks and bing cashback to make it like 215 shipped. it's nothing special of course.
i'd personally save up for a bikes direct bike at least...