The 20 is worth a lot. Around 4 grand to start off with. There was a nice one (20 gauge) around here a few weeks ago, boxed, at a show. The guy got talked down to $3500.00. But yours is a skeet- original with sk1 and sk2 barrels. That makes it worth a lot more. So, I am thinking (ballpark figure) $4500.00 to $6000.00 for starters. Depends on the condition, configuration and what the market will bear. You might get a little more and maybe a little less.