Marketplace is good.
For eg. I bough set of some scifi low poly meshes that are meant to be used for detailed maps renders (have no uvs etc.), but i bought them to have base for creating my own set of meshes. Total for 400 meshes was like 20$. Thinking about bunch of different shapes to make my set will easily take longer than 1 hour, and i have it all there ready to be used as concept art.
Ps.
I also remember when first Stalker was shipped with same textures as HalfLife. Everybody screamed “stolen textures” but it turned out that valve used some from commercial pack.