I've done this in my car. It's not as complicated as people make it out to be. Get the right parts, and you can DIY this yourself on your driveway under 2 hours.
What you will need:
1. The Janus installation kit that you see on ebay. Ranges from $100-150 for the bracket, and the plastic double-din trim piece. The german seller that you are thinking about, now has a shipper who ships from the US to minimize any delay.
2. A/C relocation kit from bmw. That will cost aroung $50-75 depending on the source.
3. bmw wiring harness adapter $10-15
Cutting of the original heater arm is very simple if you follow the instructions for the double-din install kit. There's nothing difficult at all. Stereo shops will quote you prices up to $1000 and say how difficult it is...it's not. Read up on the instructions found on e46f and m3f and you'll be good to go.
Total cost of parts should be around $250-300 plus the cost of the double-din unit.
Last edited by toy4to; 05-27-2013 at 01:37 PM.