Envato Market offers two tiers of fees for exclusive and non-exclusive sales, which you can view here. In addition to our published rates, it is possible to be granted special terms and rates in certain circumstances.
When we grow new categories or target specific types of content, it is important to have initial content to kickstart the new area. Generally we commission content, however, occasionally we also negotiate specific rates for authors who can help the Envato Market grow quickly.
If you have a sizable portfolio of high-quality work that you believe will help the Envato Market grow into new categories and niches we are not currently selling in, please contact Author Support.