Just to give you an idea of material costs. I bought a stock T6 wheel for £86, cable set for £36 and whilst not required I also swapped the stalks to ones without cruise on (as that was now on the wheel) for £44. I installed it myself and have the ability/equipment to code the van as was required. I sold the removed bits and got about £60 back.
It took me a little while to get the bits together and did land on some bargains, so you will likely pay more if you want it all immediately. I wouldn't have paid £700, but others might!