Unfortunately, I can't offer any info on shops other than what you'd see on online reviews.
Usually I ask the dealerships where they get it done and do a little research on their recommendations. If this is a business with a storefront, I get a little more confidence, especially if the dealership would steer you there.
Plus, remote starts systems have become very common these days. I'd like to believe most audio shops that get the license actually know what they're doing.
If you are feeling a ltitle DIY-ish, here's a write up from the M37 subforum:
how-to-install-fortin-remote-start-2012 ... 13141.html
I know some M35/M45s have remote starts, but I don't think I've seen any posting of where they got it done or how much it cost.