While that is a fairly nice looking bike, that frame isn't exactly an ideal fixed gear frame.

It has huge amounts of clearance, which is nice if you want huge tires and fenders, otherwise it just makes the bike flexier which is not desirable in a fixed gear frame.

And you have to use long reach brakes, which really dont generate the same power as a good set of short reach brakes.

Also, since it appears to have touring geometry, the bottom bracket is probably low, meaning greater risk of pedal strikes.

The bike is probably worth $150 for the parts, but it you need to shell out money to convert it then you will end up spending more than its worth. You can get a new fixed gear bike with much more appropriate parts and appropriate geometry for not much more money.