Like anywhere else, it obviously depends on the product(s) you are selling. I don't make anywhere near as much profit selling bodybags and wheelchairs as bond1 or Errant earns from their 'current-gen' characters and weapons. But by the same token, it takes them
much more time and effort to produce that kind of media, and it does more than just hang from the ceiling.
Take a look in TGC store at other people's products. Multiply the point value the product is selling for by the number of downloads it's recieved, and divide it by two. That's the profit that seller has earned for that one model. If you're looking to make a fast $50, you'll need to either get into weapon/character modeling, or upload several models as opposed to one.
I find it also helps boost your sales if you add media that hasn't been available before. I noticed a lot of people on the forums were asking for a wheelchair model, so I made one, and now it's one of the highest downloaded models in my account.
Kravenwolf