Any ideas on the price of a 72 4x4

[MR. GOODWRENCH]

Ok,I when to look at a 72 4x4 today,and the man wants 1200 for it,the for sale sign in the truck says 1800,so he already came off 600 dollars,all the glass is broke but the door glass is good,and vent windows are good,fenders,cab supports,floor pans,inner fenders,radiator support,tailgate,rocker panals,and the bed are all full of rust,it has a bed liner in it and from what I could see under the bed,is that the bed is junk,no tow hooks,tires are dry rotted,and I am pretty sure it was a factory 6 cyl.,because of the radiator,and engine mounts,it does have a 350 with a 350 turbo,with an inch of dirt and oil build up on all the drivetrain,the glovebox sticker is gone,and he swears it is a cheyenne,it does have all the woodgrain trim and the woodgrain trim inside,the motor does run,I guess what I want to know is would it be an insult to offer him 500 or 600 for the truck or is that to much,I mean I know what the parts are worth but I see nothing body wise savageable the hood is dented to,I wish I had a picture but I hope I have disribed it enough for you guys to get an idea,thank you all.