TV / DVD on Sat NAV?

[DDD]

I have been looking into this ever since I ordered my car, but it looks like its still as expensive as the NAV system itself to do the modification.

This seems to be the only place to get the TV tuner module and all the wiring needed

http://www.nav-tv.com/products-mini-navtv.htm

The kit is $1295 from them though!!

Does anyone know of another way to get this working?

I think units from the 97 5 series will work, but only while the vehicle is not in motion or something.