If the car starts and drives you can't go wrong with paying $1000. That doesn't mean there are not issues that may not show up until after the ink is dry on the transfer of ownership. Sitting for four years is not a good thing for the injection system. The 89's had some problems with their ECU's. Remove the sill cover on the passenger's side and then the kick panel and check to see if the last three numbers on the ECU are 951. If so it has the better ECU. The mileage at 120K is what I would consider low. See if you can determine if the odometer is working. There is a gear that breaks and if it does the speedometer still works but the odometer does not. If it has had reasonable service and the mileage is correct the engine is good for at least another 100,000 miles. See if the front end seems tight enough to be acceptable and safe. I would be surprised if the AC worked and you are liable to find other things that need some $$$ and labor thrown at them. Does it still have the original type plastic radiator that should be replaced before it cracks and overheats your perfectly good engine? If it is like most other Volvos of that vintage with those miles and you are good with a wrench it sounds like a great value.

I would expect to put $400 in parts in a car of that description to make it comfortable and reliable. Shocks, struts, timing belt, drive belts, seals, alternator brushes, radiator, plugs, cap and rotor, ball joints, etc.

Randy