There has been considerable interest in long-range active Radio Frequency Identification (RFID) for use with home automation systems.
One can get a set of active (315 MHz or 433MHz) RFID receiver (with RS-232 interface) and transmitter PCBs with a claimed range of 8 meters (keyfob)
40 meters (car accessory) for about $50 depending on device, enclosures and antenna chosen.User guide, FAQ, VB demo ActiveX control are available zipped up here:
There is an active Homeseer forum about these devices and HS plug-in development:
... Marc Marc_F_Hult