Cost of a good used DDEC 4 12.7?

Should be finished by Monday evening. Before starting it I’m going to have them put oil in spray bottle and spray in the gear case and under valve cover to try and prevent dry start. But most parts on the engine still have bar code stickers on there hopefully it’s a good sign of previous owner taking care of it. Also the mileage is only 680,000 on ecm which is original