IIRC Adi priced up the kit fully assembled.
The ECU itself assembled is this one http://www.diyautotune.com/catalog/m...unit-p-56.html then you need a couple of additions for the idle control, coil driver, the MAP sensor upgrade and boost control if you want it.
As you say it would be worth ordering the cabling at the same time (if you do decide to order from them let me know as I'm after a wiring pack from them ;P)
I suspect that it would be a case of contacting DIY Autotune and telling them which kit you want and what options you want included and they will then be able to give you a price.