The first fork in the road: Do you have this steel framed road bike already?
That's the biggest hurdle. After that it gets easy. You can go faux-fixed with a singlespeed really cheap, $10-20 if your lucky. Going fixed has to balance cost against compromise.
My initial conversion of the Pug to singlespeed cost me $100 for a new wheelset, only because the old Maillard Helicomatic hubs were crap (
http://www.flickr.com/photos/unregis...7602237432523/)
The conversion of the Purple Mistake is probably closing on a $1000, only becasue it's been a labour of love (it was my fathers bike)
http://www.flickr.com/photos/unregis...7603220672327/
The link to Sheldon is a good starting point
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This is Africa, 1943. War spits out its violence overhead and the sandy graveyard swallows it up. Her name is King Nine, B-25, medium bomber, Twelfth Air Force. On a hot, still morning she took off from Tunisia to bomb the southern tip of Italy. An errant piece of flak tore a hole in a wing tank and, like a wounded bird, this is where she landed, not to return on this day, or any other day.