Simply for commuting, can I get away with buying a cheap $200-300 fixie or will I regret it?
From what I've seen "cheap fixies" are an exercise in style over substance lacking quality control and what reliability such a simple design should deliver, and simply doesn't.
A more upscale new FG machine will at least be light(er), properly aligned and durable but attractive to the inevitable thieves/vandals in a commuting environment.
A low cost/high-ish performance/stealth-ish FG commuting machine can be converted from a properly sized horizontal dropout '70'-'80's road bike with fittings for mudguards, racks and the inevitable "stuff" commuting in all weathers with a variety of burdens requires.
Here's how:
Fixed Gear Conversions
-Bandera