I can tell you the buttons and joysticks will not come with any wire.  But, I don't think you need to buy the wire from Happ.  You could just pick that up at like a radio shack along with the quick connects, stripper, etc.
The joysticks won't come with any mounting hardware so you'll need 4 screws or bolts for each one - local hardware store. 
Plus, if you don't have one, I'd get a multi-meter (Radio Shack) to help in the wiring process.
Good Luck.