I think at this point it's still difficult to lure players for chinese clubs. They offer immense wages, we all know that, but that's not convincing everyone to give up a future in football.
They are limited into signing those, who actually want to go there, and those are relatively few and there is no alternative to them, that's why chinese clubs forced to pay the huge prices that the selling clubs demand. They can't say "oh ok, Zenit want's 90m for Hulk, thats too much maybe I should go with Saio Mané for less instead" because Mané might probably not want to play in china.