I am trying to figure out why you think you should be able to resell someone elses work?

Why would you be able to upload anyone elses models or figures to the store?

As to game-dev licenses, those here at Renderosity are about on par with those elsewhere in other game-dev websites.  Some vendors do have much higher extended license fees.  This is if you are using those assets in some form of 3D in the game and not just generating sprites and clips.  Often times Game Dev specific products include some format compatible with Collada, FBX, Unity, or unreal.  You are paying to save time making assets from scratch, and for use as 3D interactive assets it involves redistributing some form of the mesh and textures.  Not all vendors want this which is why not all content has the option.  

The alternative if unable to make your own assets for whatever reason  is to hire creators to work directly for you to make assets.  Then you need to either negotiate a per-asset rate or an hourly rate.

The New HD Toaster from Wamco toasts bread more evenly and acurately than Standard Toasters. Take advantage of the FULL resolution of your bread and try one today, because if your toast isn't in High Definition, you are not getting the most of your toast!