No sense in PMing it, too much secrecy around here *lol*. I don't have a problem w/spelling out my costs.
Tail lights - $325 -
http://www.e90post.com/forums/showthread.php?t=672133
Trunk lid - $600
Coding - Done by Benvo more than a year ago when he did some other random stuff for me, so I can't give you an exact price on that, as it was part of a package of options
Cable - I have my own
Since so many parts from non-M E90s fit the E90 M, I spend a lot of time on e90post perusing their threads. Found all kinds of interesting things to retrofit, like the rear seat 12V adapter retrofit (rec'd the pieces for it a few weeks ago) among other things. Prices are generally a little bit cheaper than here.