Well its not all about cost and authenticity for some people, some like experimenting with lots of different controllers, sometimes swapping out actuators, springs, switches etc to make something that really suits them, something personal.
Grouping all knock off's as inferior might be short sighted, as randy pointed out there are lots of variations, some will be better than others and some may even surpass the originals they where cloned from (tighter spring, shorter throw etc).
Lastly as pinballjim mentioned, some knock off's are so good, you cant tell the difference.
With all that said, without trying that specific model out, its hard to pass judgement, all we have is an educated guess.
Does anyone know why happ controls are so popular? Is it just down to nostalgia/familiarity/durability, or do they outperform other brands in some area? I have watched a few different broadcast competition events, and the top tier players always use jap controls (sanwa/seimitsu)