Flyman, I have 8 freewheels, 2 of the cheap ones, 3 of the slightly less cheap ones and 3 of the $80 HD ones. I have put a combined total of several thousand kilometres on them and so far have not noticed the cheap or expensive ones wearing out. I have two freewheels that came with no detectable play in them and they are still tight hundreds of miles later- one is an $80 HD, the other is a $20 standard kit item. I am very happy with these two, the other six have various different amounts of play in them and have been like that since new but haven't gotten worse.
edit: note- all six of my chinagirls are standard unmodified engines.