There is another make [Proxalert R5 Aircraft Proximity Alerter] shown at :
http://www.avshop.com/catalog/produc...productid=6265
(sorry, I don't know how to do "here") for $799. That shows range and height but not bearing/azimuth of possible threats. I don't know why it needs the serial port, antenna and audio connections which it has on the back - looks like more to the installation than just velcro on the instrument cowl.
Some users have posted comments about it, e.g. "After flying with it several times in Chicago I can say that it shows a lot of false targets. I noticed that when I turned off my DME and transponder that it seemed to be more accurate. Having said this, I have also flown with it side by side with a trafficscope, and have found that the trafficscope does not get the false positives that the proxalert did."
And: "I recently purchased a ProxAlert R5, and I would like to thank AvShop for their excellent service and to congratulate the manufacturer on their very impressive design. I have now had a chance to install the R5 and fly several test missions, and I am glad to report that the ProxAlert offers outstanding performance in assisting me to spot traffic, especially while flying solo. For several years, I had been using a first-generation traffic spotter (Monroy 200), but the overall assistance was very limited due to false alarms, missing alerts, no squawk or altitude information, and so on. I really wanted a better method, but did not feel like spending the $10,000 or more for a Ryan. The sophisticated design of the ProxAlert provides all of the features I wanted at an affordable price. It seems to have excellent sensitivity, and the ability to track each alert by it's squawk code is a great advantage in developing a mental map of where the other aircraft in the area are located, especially while monitoring ATC. All in all, I find the R5 to be an outstanding addition to my cockpit."
(I have no connection with any of the above, other than an interest in the value of such things.)
Chris N.