SureCheck Aviation is offering a low-cost-just $595-portable traffic proximity alert system, the TPAS RX-100, that detects the presence of transponder- equipped aircraft nearby. The portable unit is not TSO'd, and the information it presents, just like that of a handheld GPS, is completely advisory in nature. Not surprisingly, the unit is low on features, compared with FAA-certified units costing $25,000 and more. It won't tell the pilot, for instance, where or how high the traffic is, and it only displays the distance to a single target, the nearest one. Still, it is the least expensive traffic alerting system we know of. For more information, call 888/340-8055.