Back in the day, kit radios were about as advanced as you could get with DIY electronics. You can still buy kit ham radios but the advancements that have been made in what is available for hackers is enormous. A full fleged computer the size of a deck of cards is amazing. This guy built an incredibly complex security system using off the shelf components that could have easily required zero soldering had he only used wireless sensors. His design is maybe a little over engineered (tamper switches on junction boxes?) and is probably much better than what any residential alarm company could offer.