brickshooter:
For $100 for an ultra-fine brush, I'd go with the Badger Sotar. It's neck & neck with a Micron for detail work. Probably sits between a Micron-B and Micron-C.
It's not just the size of the needle and nozzle. It's the small feeling of the brush, the lighter cup, the "pointability" of the brush that allows one to do detail work.
The size of the nozzle matters. But the taper of the needle counts more. (Badger calls the needle taper cone angle "linear airflow angle".) Try to get one with an angle of 5-6 degrees which indicates a long and slander taper of the needle. And avoid needle with a double cone. These is important in painting "ultra fine lines". Don Wheeler gave some measure of different needles on his website.
If the manufacturer does not post of the size of the nozzle, be careful about that airbrush.
I like the medium weight (about 100-110 grams with gravity cup) and well balanced airbrush in my hand. Light weight AB does not feel right. But this is personal.
Chinese knockoffs have quality control issues. If I were to get one, I'd swap out the needle and trigger for a Iwata needle and trigger. Then tune up the brush a little.
I have not seen one single konck-off that you can use the Iwata needle on. They were made different in diameter on purpose to avoid copyright issue. You are right the the Chinese needle is not up to the standard of Iwata, but it may not look too bad (in shape, polish and springiness) compared to some American made brand.