Call around, you should have many BMW dealerships within 50 miles of you. Might be easier if you get the part # off BMW's site and give to them when calling, that way they can know exactly what you are asking about. Most will probably try and hit you up for a couple hours (or more) of install time, but BMW stated 1 hour install time when it came out.
Got mine at Union Park in Delaware for $700-ish when it first came out...it was discounted...plus, no sales tax. Otto's outside of Philly had decent pricing, as well. Don't forget to mention BMW Car Club Member, if you are one, that should count for a little discount, too.
2011 335i M-Sport, BMW Performance Powerkit Version 1, BMW Performance Exhaust (FOR SALE), 35% F1 Pinnacle Tint