Looks pretty good to me. If you build it exactly like that I doubt that you'll have regrets. You may want to shop around a bit for parts. Just as an example, the crankset is available for less at Amazon -- or preferably the x9 version is available at Amazon for just about $10 more. Amazon is usually not the cheapest source but they are very reliable.
Have you checked out Niner's headset? Probably cheaper and bound to work unless they re-arranged things for the newer models.
Why not start tubeless from the get go? It won't save you money but is worth every penny. You'll need valves and a bottle of Stan's. Get a tube anyway to deal with on trail flats. Read up on how to set the bead if you don't have access to a compressor.
You'll need brake adapters and grips but you won't need brake wires. Your brakes will arrive assembled and pre-bled.
Good luck and have fun.
