the electronics can be programed to a new car. I haven't had to buy a new key for the jeep, but when I had a saab at the dealer a cut key with no electronics $15, electronics $350 + programing. but you could buy the cut key from the dealer and electronics off ebay for $40. save yourself 310 bucks. New cars with the factory system come with 2 keys. you can probably take it to the dealer and just get a 2nd key. I know they are not all that expensive. or buy a used key off ebay, take the electronics out, buy a cut key from the dealer and get it programed.
1989 Cherokee Pioneer
http://goo.gl/OspLWH - amazon link