After an extensive search for a new, fully constructed, inexpensive, single-speed road machine, here was the result:
Obviously there are many brands on the market, and if you're looking for something cheap, I suggest, *gulp*... brace yourself... "Made in Taiwan". After living and riding a bicycle everyday for two years in Taiwan myself, I became well acquainted with the extensive bike industry on the island. Quality built man powered machines, at a fair price.
Recently in California I found a single-speed Giant with a very decent steel frame, for 450 USD. A bit on the heavy side, but still a comfortable ride. Very generic brakes, cheep wheels, etc. but hey, after only 450, you could easily do some future upgrades if you you're on a budget. This was the best deal, money-wise I could find. I test rode this monster, and almost bought the bastard, until I had a chance to lay my hands on a 2006 Specialized Langster...
The Langster runs at 600 USD and is, in my humble opinion, the best quality single speed bike for its price range. The Langster has a very lightweight, aluminum frame. Construction quality surpasses the Giant in every way. Converts easily to a fixed gear by flipping the rear wheel (for all you fixie fanatics out there). Originally I was gearing towards the 2007 model, but if you can find it, check out the sleek matte-black frame exclusive for the 2006! This pretty much sold me. I look forward to upgrading to a carbon fiber seat, new wheels, cranks, etc., as cash flow permits.
While building a single-speed from scratch is probably the most ideal, if you decide to go for a prebuilt, I wisely suggest: LANGSTER.