I think Bruce from WI had one for sale here a year or 2 ago, and it took forever to sell. I think he was asking in the 2-2.5k range. I wouldn't mind one for a daily driver. I want to move my 89 F150 4x4 for something more economical. Don't do much hauling anymore.
If it's a low mileage car in excellent shape, I've seen them go for $5-6k. My brother has an '87 with only 67k miles on it......SOLID car. His boss/landlord plans on buying it from him for $5500 or so. The '88-'89 did have the better engine, but the '87 had the one year only GN style interior. My '88 had the entire interior from an '87 installed in it. :TU: I still have the original black int. from the '88. Go over to the LeSabre T-Type Forum and ask around. Not sure if you're looking to sell or buy. Someone over there will give you a good ballpark figure.