dont buy cobras bc they suck at detecting Ka band which most cops use.......i have a bel, they make solid detectors.  Valenetine and the Escort Passport are the two best but not everyone can drop $400.  Mine was $110 and has saved me thousands in tickets so i cant complain.  The best example was when i was dricing back roads at 3am diong about 110 in a 40 and i came around a corner and it flipped out.....i slammed on the brakes and passed a cop about 15 seconds later, more than enough time to slow down.
www.radarreview.com is a solid site with good info