That bike seems overpriced even for a flip-flop (which seems to double the value of a bike) so I would say $150 if it is in great shape, and fits you would be a more reasonable price. I wouldn't pay it, but I am already fixed, and I don't need my bike to be.

I don't understand why fixies are as expensive as geared bikes (or more) I would think BikeDirect could sell one for like $129 if they wanted to, but that's a different thread.