If a person were to buy the $299 Shapeoko v2 kit, what “electronics” do they still need to purchase? I assume one would need to provide their own Steppers, Controller Board, Power Supply, and Wiring. Anything else? The Inventables page doesn’t specify. https://www.inventables.com/technologies/desktop-cnc-mill-kits-shapeoko-2
There is a list of “contents of the mechanical kit” listed in this blog post from inventables.
They go into much greater itemized detail at the bottom of this blog post: http://blog.inventables.com/2013/10/shapeoko-2-now-available-for-preorder.html
Edit: Marc beat me to the punch. Oh well.
You will need motors, if you are looking to cut Alum I would go with nema 23.
Thank you! 
The big parts not on your list are a spindle (DC Spindle, trim router, something along those lines) and endstops (some a314x Hall effect sensors will be cheap and work well).
I made a list here : http://wyolum.com/shapeoko-desktop-cnc-mill-build/