I have an 05 z so i brought the cubby hole from a 03 z. The unit it self is £113.00 shipped directly from china. Then its really just man hours. But because i work in a PC workshop i have had alot of tools and bits at my disposable.
When im finished im looking to write up a full detailed guide
Very interesting may look into this myself, because if i can build this surely i will be able to do the same as you(industrial sparky).
Basically what you are doing is buying the unit off ebay, pulling it to bits then fitting it into the console?