Originally posted by VisualDarkness Weather sealing means extra steps during assembly, tighter tolerances, possibly a different material choice and additional quality control. The downside is that all of the things stated equals higher manufacturing costs and in the end a higher selling price.
I think the sealing costs less, or certainly not more, than having shake reduction in the lens, or at least it offsets it, so Pentax lenses with WR shouldn't cost more than competitor lenses with SR built-in. It seems like the majority of competitor lenses are coming with SR now so Pentax should be able to compete while still providing WR. And as for quality control, certainly my experience with the 55-300 DA vs. WR doesn't suggest that there's any more quality control going on in the WR.