need help to fig out value of a 1972 duster

you would think if hes wanting to sell and i have the cash he would be a lil more friendly...if its a real 340 id pay what he wants...but he said 6k no matter 340 or not and wont budge..i offered 5,500 and he blew me off..so im still searching for somthing either A or B body type mopar..