so ....do you actually want a single speed/fixed gear bike or do you want a multi gear road bike.
I think a decent used road bike can be had for $200 on Craigslist with a bit of patience depending on where you live. It may be 20-30 years old with downtube shifters but so is one of my bikes and it's still a joy to ride and truth be told I'm almost as fast on that as I am on my modern bike.
You definitely should be able to find a used fixed/single speed for $200 or less if that's what you are after. If you want new Bikesdirect has some good deals but I would spend at least $300 for a ssfg from them or $500 for a road bike miniumum