It all depends on finish. I've seen some crusty ones go for under $100, but I've seen some really nice ones go for over $300! The .38-55 is not the most common, but not a rare one either. Something inbetween. I believe the .40-60 Marlin caliber is the most often found.
Might check the relaoding tool web site. I think they have a lot of serial numbers listed there, as each 1881 tool was individually serial numbered.