No, title does not say it all, far from it
so I'll have to make a few assumptions.
Assuming it's used, in excellent shape, Moonson MA manufacture, and that's it's a model with interchangeable barrel (DW made a few with fixed barrels but I don't know if they came in 6"): I'd pay about $200-230 because there is only one barrel coming with it. If the barrel is interchangeable and there is no lug-removing tool coming with the gun, figure an additional $25 or so to purchase one from DW so I would not pay over $210 in that case.
If it's a used but recent model, I would have no clue as I haven't seen any of those in used condition and in .357 (or .44 for that matter) for sale. This doesn't surprise me
Of course, that's a general ballpark and your mileage may vary. 6 months or so ago, I didn't know much about DW and after reading and asking on TFL (and buying a used DW), now I'm giving price advice, ha! The blind leading the blind...
I hope this helps nevertheless .
PS5