Here are the scanners from Radio Shack available for $150 and under. You'll probably have to google for reviews of these. I have the Radio Shack Pro 94 which works great. Obviously any scanner is only as good as where you're located in reference to what you're listening to. I live about 9 miles from ORD
and cannot hear any ATC, just the aircraft side.
Radio Shack Scanners
This website is also a good source of info: