Is it too late to wire your house(already sheetrocked)??? The glassbreak and motion detectors can be put in (wired) later, but getting wired sensors on all doors and windows needs to be done before.
Putting wireless sensors on all doors and windows CAN get cost prohibitive if you've got alot, at which point, you end up with mainly glassbresk/shock sensors and motion sensors. The problem with that (incomplete door/window sensors)is that you can't arm the motion sensors when you're home, and if someone quietly jimmies a door/window open at night when you're home, you get no alarm.
As far as DIY wireless, there's plenty on the market. FWIW, my in-laws put in a Simpli-Safe system, and have been happy with it.
