Well Envato/Themeforest need to work this out for their own good. Until they can provide a reasonable solution to this, I am, whenever possible (which is most always), I am buying directly from the Developer’s website or through other theme marketplaces. The Developers are not exclusive to Envato.
For example, say one of my clients finds the new Churel Ghost theme on Themeforest (the Developer of this theme is Themeix) that they want to use for their site, and they want me to make some modifications to the theme, and/or they want me to add some extra features (i.e. update a v2 theme for compatibility with Ghost v3, and add Memberships features because they will want to charge for some of their content.)
In this case I have the choice of buying (or directing my client to buy) the Churel theme through Themeforest for $900.00:
(Screenshot of Churel on Themeforest):
I can buy (or direct my client to buy) the Churel theme directly from the Themix website for $39.00:
(Next 3 Screenshots are also Churel, but directly from Themeix - the Developer’s website)