Share 'Building vs buying a singlespeed cross bike'

Open to any and all to respond: Pros and Cons of building my own vs buying a prebuilt singlespeed crosser. If you suggest buying a model, what are your recommendations? If you suggest building, I am a Cannondale fan, so that would probably (but not definitely) be the frame of choice. After that, recommendations on hubs, cranks, chain, wheels, head sets would all be very welcome. Oh, and unfortuna…