I sold an 01 CR250 for 2500 that had a pipe, fresh top end (which every bike for sale will claim), new tires and chain back in November. An 89-92 should be no more than 14-1500 from a dealer, or 11-1300 privately. IMO
Don't get taken, when you find a bike you like, look at the online classifieds to get an average price of what it SHOULD sell for, and take a friend along to looke for spent engines, wheel bearings, fork seals and such. Plastic, tires, and chains can be reletively inexpensive to ride.