Ebay gives all sorts of realistic projections, try completed auctions and go from there. Actual research there and elsewhere may take some time however, but if you want to do it right, you will have to do it that way. Currently past week or 2 there has not been a sealed Chase up for sale, so you may just have to list it and see what happens. Maybe the better question would be, how much do you think we would be willing to pay, or can pay for it right now???