Having just bought a 9C1 for the first time a few months ago, I can give you some good advice.
First, most police depts retire their cars around 120k mi - I'm curious why these have less. Were they local cars? In that case, check the suspension real good to make sure the cars aren't worn out from around-town work. They may also have crap interiors, and if you (or your wife) care about a nice interior, that's an issue because nice interiors are expensive to retrofit. Mine was a '95 9C1 with 122k on it, runs perfect, is extremely quick, has no rust and a near-perfect interior and I paid more than $3500 for it, so you're on the lower end of the spectrum but the cars you're looking at may not be top-notch either.
Second, CHECK EVERY SINGLE THING ON THE CAR BEFORE YOU BUY IT. If the guy gives you a hassle about how long it's taking, tell him to shut up or you're leaving. The two things I didn't check - front brakes and front tire alignment, ended up costing me close to $400 for new brakes, tires and alignment. That's 10% right there I could have talked him down, but didn't cuz I didn't know.
Third, what to look for: 9C1's were used for several different things: marked patrol, unmarked patrol, administrative (DMV, detective, FBI, etc.) or non-police (fire, medics, etc.) and each car has been treated differently - you can figure this out (I listed from hardest to easiest). They were also appointed differently - some have all vinyl seats, some have cloth, some have rubber floors, some have carpet. Decide what you want, because it gets expensive to change it later.
Fourth - my own experience:
1. rubber floors are waterproof, clean easy, unbelievably easy to run stereo cabling underneath
and don't transmit any more road noise than carpet (a concern for me).
2. You will miss POSI (G80 option code) if you do a lot of stoplight racing or drive a lot in the rain without good rear tires. My buddy in a Grand Cherokee 5.9 Limited loves to mess with me when it's raining, because my right rear will spin with the slightest amount of gas coming off of a stop. On the highway though, I smoke him
3. Print out and be familiar with the complete RPO code list before you go look at the cars. This tells you what you're getting AND gives room to negotiate.
4. CRUISE CONTROL - if you drive much highway, you will miss this. The LT1 will creep up way beyond the speed limit before you ever notice it if you just lock your foot and go. I just bought the whole cruise setup out of a '95 Buick Roadmaster wagon for $75 and installed it myself, so you can go that option, but it's a lot easier if it's already on the car.
5. BRAKES - check the brakes good, because new pads and rotors for this car are $$$$.
Dang.. it's 1:03am.. I need to get to sleep. I'm in the middle of mod-o-mania:
stereo, remote starter, cruise control, Blazer overhead console, Z28 cluster, Fleetwood trunk carpet, bonneville seats, dual hood lights, summit mufflers, Kumho Ecsta STX 255/60R15's, my own homemade RAISS intake... where will the madness end????