To Bike Forums, Edmund!
Edmund, your best bet is to continue to research Craigslist. Find a bicycle with a chromoly steel hybrid or road bike frame and upgrade it in time.
Additionally, you could join a bicycle co-op. Volunteeer enough time to become a member and locate a donated steel frame, through the co-op. You can begin to build and upgrade your bike right there at the co-op, under the leadership of skilled bicycle mechanics.
Alternatively, you could order this really nice single speed online:
www.nashbar.com/bikes/Product_10053_10052_504148_-1_202339
Good Luck!
- Slim