Poly count affecting renders is based on individual system specs. The more polys in the scene, the more powerful your system will need to be in order to keep Poser running. The poly warnings in the descriptions were simply put there to assure you know what you are dealing with before buying the product (or at least, that's what I assume, since I didn't make the package.)

As a comparison, I believe V3 base is about 8MB. Use that as a starting point to determine if you can fit enough of those objects in your scene without your computer choking.

Hope that helps!