Most of my packages have come at this point.
After work today I made it my mission to figure out what I wanted to do with my Aux in.
I swapped out my CD53s. The 03 July unit I got had a bit of messed up faceplate so I swapped the faceplate from my original radio. Interestingly enough, Xexilia was born 8/30/2001, and the radio installed was a 01 May. I was afraid I would have trouble with my ultimate mounting position but it was surprisingly easy. I was able to route it into the armrest in the tray position next to my factory CD holder. I wanted to just throw out the cd holder portion, but I couldn't get it to separate.
Now with this install, I wanted to get aux in and Bluetooth while spending under 200 dollars. I also wasn't all that interested in an aftermarket radio. That means I was left with either genuine OEM equipment, or aftermarket accessories. The best aftermarket option I found was the GROM kit. However, my understanding was that it deleted some OEM equipment and the Bluetooth adapter made this setup beyond my planned budget. To go with the OEM aux in I would need to update the CD player to one post 02 September. Prices on these can vary. Also, these radios are all flat pin harnesses. I'm not sure if flat pins are standard in all X5s, but in my 2000 528i I needed a round-flat pin adapter cord. It was OEM custom ordered, aka EXPENSIVE! I would not have gone this route if my X was round pin. So I replaced my OEM radio with another OEM radio. I added a now compatible OEM aux in kit. That only left the problem of Bluetooth. I searched and found others were using Bluetooth receivers with a 3.5mm adapter. I found the cheapest option on ebay and then saved another 5% with a best offer. It got a bit dark before I could take some photos so that will be tomorrow. Now I want to split into the rear dc outlet and add a dc outlet in the storage of the arm rest to constantly charge the bt dongle as well as hidden storage and charging for phones, etc...
BT dongle
Bluetooth Receiver Car Hands Free Kit Wireless Music Streaming 3 5mm Adapter Aux | eBay
Aux kit
Amazon.com: BMW Genuine Auxiliary Audio Input Cable Adapter for E39 5 Series (09/2002 and on), X5 (10/2002 and on), All X3: Automotive