As to value, you have the 2 barrels that are most desiable for hunters and leats desirable to chooters/fro carry. As it is with all you have that is worth around $800 if some one who wants it to hunt with is looking for one (and they usually are as to a nice Dan Wesson whoich that is a nice one). Now it could go as much as $1000 but $800 for teh set os a good average. IF you were to buy the , 4" and 2/5" barrels an dschrouds for it in as good a condition as your ciurrent ones are, you would have an easy $2000 set there woith the additional 2 barrels. The best indicater is check out teh past and present auctions at brandx
and you will get a good average as to value. Now with that said, you are in Canada and I am not all that up on the laws to get it imported to the US. i would expect though you would have agood chance of selling it in Canada and would most likely get a good bit more for it there.
Hope this info helps. I have a DW model 15 with the 6" and 4" barrels. I love the way they shoot. Very reliable and accurate. Also there is a company EWK Arms that sells DW barrels, schroudes, and other parts/accessories.