The cheaper Chinese duplicates, the cast finish is not as good, lower build quality overall but some people have been getting good results, they do need some seeing to. I know the actuators need adjusting when put on otherwise they won't last. Personally ring R-tech nick has been harassing these turbos for a few customers as well as hybrid experimenting with 360bearings etc.
For a second hand k03s it's what £200, k04-001 copy is £250.