I recommend using a Uniden 120XLT Scanning Receiver which retails from specialist electronics stores for around $294 if you
only need the basics. A Uniden 3000XLT Scanning Receiver retailing at $429 if you wish to listen to some Federal Police traffic around the 27MHz range as well as regular officers. Or, if you have money to burn a Yaesu VR-500 Multi-Mode Scanner at around $850.