Thank you for your information.
Speaking about rules, there are rules you guys roles out about a month ago for pricing promotion.
It's because you guys don't take any actions or too little actions I am not sure. So you can see for example on new WordPress themes page here https://themeforest.net/category/wordpress
There are multiple items price at $19, most of them don't show clearly when promotion price will end and there are many rules you can check there.
The same as popular items list, some themes are running promotion forever! there is no ended date. This is one of the reason why items price is going down.
I am not against all pricing promotion or reducing price, it's author right to do that but there should be some limitation or at least make it clear for customers when it will ends or if they are sure they want to sell their theme for $19 forever and survive. That's fine. I can wait and see.