shoulda called the police as he saw the guy breaking in his car then gave the license plate # in case he drove off with it or like everyone said walk over casually then go ape shit once he was near

Depends what you buy I guess? My dad paid $395 for the units and pays $25 a month for the service. It works great, after having his last trailer stolen he won't risk not having it again. It probably isn't practical in this case though, I'd probably just buy a club.

I'm assuming he's got his keys now.

A low tech solution - go put some kind of anti theft device like a Club on it. Not foolproof, but it's a deterrent if he wants to stop the person from stealing his/her car.

Also remove valuables from car.

Rekey the locks and reprogram immobilizer if it has one. If you don't want to get ripped off by the dealership, see if you can find a locksmith that does automotive locks and see if they'll rekey it for you.