So after having spent some time reading the valuable find lists it seems that many of the artifacts basic form, crown or pendant etc, is covered on the list, at around 4d6 gold coins each.Of course, while I said “you can’t total materials and labour”, adventurers in your players’ position may very well be tempted to. So your peddler might pick up an artefact sword and be able to value it as a very good looking, finely worked, sword, worth twice, maybe three times whatever that type of sword costs in the gear table. But that is likely to be a underestimate.