How "loaded" the truck is with options, how clean and straight it is and service history would affect value. I paid $9000 for my '96 with 351,000 on the clock but it was in pretty nice shape and 1-owner with several new BOMB items recently added. I think I could've done a little better though.
Being a '97 is a plus because it's considered the best of the 2nd Gen 12-valve trucks and has hydroboost brakes & steering. I say this because the '98 12-valve engine is a bit of an odd duck (built out of the 24-valve block, having some different fastener dimensions and more than a couple different pumps).