The price may be high. NADA books it at $7450 to $8950 and you are at about 71,000 miles. I might go as high as $11,000 if, tires are good, maintenance records, roof good, exterior good, runs and drives very good, no signs of water damage, etc. Still you will probably put another $2000 into it. The reason I say it's priced high is I paid $12,200 for my 03 Chateau 26Q in January and it was in very good shape and at 48,000 miles and I have put about $1500 into it. Mine books for $20,000 because of the 8.1 Vortec.
Go drive it, but I would probably pass unless they are willing to come way down.