I just did the retrofit as well, here is a brief overview...
I bought a system on eBay from a Lithuanian seller. It included everything necessary for the upgrade. I was promised a US version CIC but received a euro version with the excuse being a shipping mixup. I specifically wanted the US version for HD radio and US maps. Delivery was prompt and well packaged.
The install on my 08 328XI took longer than I thought although if I ever did another one it would be a breeze.
Coding was done by BMWretrofit. Vlad is very accommodating and easy to work with. I was disappointed when as first approached Patrys but he declined to help and told me he only codes cars if you buy his equipment. I would highly recommend you contact Vlad at BMWretrofit if you need coding.
The coding went well however we couldn't get my BMW assist to work, apparently the software in my TCU needs updating.
I'm just waiting for my emulator to arrive after which I will install US maps. Vlad read my CIC's VIN so I can order an map FSC.
Cost when completed will be approx $2100.