I paid 4500 for mine when I bought it. She was really clean too. That was about 2 years ago now. It had 33's and a 4 inch lift. Mine is an 89 as well. I love those trucks, yours is very clean. Check out ck5.com, you may have some luck selling it on there, I have also seen clean ones go for a mint on ebay. Gas prices seemed to have killed their resale, I remember them going for upwards of 10k lifted before the gas spike.
http://i116.photobucket.com/albums/o...TruckSmall.jpg
G0od luck with your sale. Really nice truck
~Brian