If you are looking to pay that price, what more would you expect for $20? With an X10-to-Insteon converter we should be so fortunate we can get motion detectors that cheap. I personally hate using X10 for how unreliable their stuff is, but since motion detection in general is just as “best-effort” as X10, I somehow don’t think I’d be too bothered using it. The fact that most of X10’s problems are powerline related, while their motion detectors are purely RF, make it not so bad.
Not that I would use this kind of setup for anything mission-critical like a security or access control system. But for 20 dollars…
I’d like to second the idea of an insteon motion detector. Just a simple plug-in unit in the form factor of an ApplianceLink with a set btton to link it to another device.
While we’re talking about security, an Insteon enabled audible alarm that could be set to link a device to a particular alert tone or recorded message would allow people to setup a simple all-insteon security system fairly easily.