why not have two categories of free stuff - one for allowing commercial renders and one not for commercial renders.  And then in both groups in the readme it could say, don't sell my meshes but your renders are yours.
ie let the person who wants to make renders know immediately prior to download, and the guy who wants to sell other people's meshes find out after he downloads it and installed it that he's got the wrong thing hehe, instead of us doing that for once. Actually I doubt that would be anyone s none of us want to sell other people's meshes.  we use poser to make renders.  The people who take meshes and resell them wouldn't be looking at readmes anyway.  
Love esther

MY ONLINE COMIC IS NOW LIVE

I aim to update it about once a month.  Oh, and it's free!