If a person puts up a resource, like a PSD/styles/actions/brushes, that links off-site to where you must buy it, should DeviantART make it so you can filter searches to show only free or premium items?
I say no. The more you allow payable resources the more they appear. I dont have nothing against this type of making money with styles that avarage designer can create by himself, but it should stay on sites related to it. From DeviantArt point of view, it could bring some good relationships with sites like envato. But from user point, its not worth it.