Unfortunately, unless you find a used one for less than $400, you're stuck buying a new $500 scanner. As was pointed out, it looks like a lot of the "good" stuff is digital on that system, and digital scanners are expensive.
The digitals are: Radio Shack Pro-96 and Pro-2096, and Unidens are the BC396T and the BC996T. Some older Uniden 796D's and 250D's can be found too, but lack a lot of the features of the newer models.
Don't worry about Radio Shack scanners, especially the digital. I have a couple of them and they do a great job. No, I'm not a diehard R/S type - but they fit my needs. My next scanner will be a Uniden, because of different features.