tony-

check out tavonnav.com

they have what you need. you can either go the full route (TV tuner), or the cheaper unit that plugs in line and does not require the TV module.



as far as a custom cable, i think i built one of the first custom AUX cables for $2.

it has 3 simple components. this was a prototype quickie -- search in my 'bin of electronic parts and bmw connectors' and viola:

check out:
http://www.xoutpost.com/showarticle-113.html

recipe:

2 capacitors
1 resistor
2 RCA ends

and the hardest part: 1 3 pin BMW connector (salvaged from the broken mike of my 2001 BMW); it was a female connector if remember correctly.

if you can get the right connector, you can have AUX in very easily for a mere fraction of the cost...