Any used stock injector is going to be considered a core, and will fetch $200-$350 a set depending on mileage and condition. To put things into perspective for you I am trying to sell a set of 90k injectors for $300. They've been listed for a couple weeks now.
If you want to get more than that out of them, throw them on ebay as singles for $75 a piece.
If you are looking for a set of 'project' injectors, you already own them. Tear 'em apart, hit the pistons with a flapper wheel, run abrasive media through the nozzles and call yourself Farmers Diesel.