Trading is illegal. Also it is very much like redistribution and its disrespectful to the modelers who spent there time making the model.
How would you like it if you made something you put it out there for people to BUY and people went around giving your model out or trading it? I'm pretty sure that you may think "oh well I don't care." But when it actually happens to you, you will notice the pain and what it feels like to have your model traded. I have had this happen to me and it sucks. It hurts.
Also if you don't get my fact of how trading is like redistributing a model this is what I mean,
You are posting a link and giving it to some