Hand finished movements with many parts cannot be replicated at a cost that is justifiable to spend on a replica.
Also to fabricate such a complicated movement would require actual knowledge of haute horlogerie as well as some previous materials ( jewels, etc).
Finally most of the finer watches have special material, either precious metals or some hybrid material which is difficult to fabricate.
So in the end any watch above 15k with an open caseback will not be replicated to reasonable perfection due to either difficulty or cost of manufacture.
How much would you pay for a fake 15300 if it's almost perfect except slight flaws?
I would not pay more than 3000. I'm sure it would cost more to make such a thing with the movement finishing.