Hi Ryan,
Sorry mate, only just seen your reply. I think it’s probably cost me a little under £400. Most of that was the initial cost of buying the TomTom unit (although I have seen them much cheaper on eBay since "typical").
It does take quite a bit of tinkering to get working as it needs to be wired into the ESP unit and the cars CAN BUS system, but if you’re electronically minded you shouldn’t have a problem at all.
I’m still working on getting it working 100% correctly. I’m going to have a good go at it again this weekend so il let you know about the result and some more information about how it all connects up. I’ve used it on two long journeys now and it works great, I’m just interested in being able to turn it off when I’m not using it so it just displays the time and temperature.
Luke