Here's some initial pricing info on the iPod MINI kit from Apple and BMW (again from foolsdragon):

Pricing for MINI's iPod I/F kit, part no. 65 11 0 392 139 is $149 retail. The kit is listed as being avaiable later this summer.

Fairly good pricing considering the ICE-Link is $200. Hopefully will have a better understanding of it's functionality soon. I'd like to think it's more than was explained in this previous post.