Buying to China is like playing the casino: you can win more than lose if you are a good player; at least that is my approach. If it turns out that the bearing works well your investment turns to be good, if the bearing is bad you lose just 1$ each bearing. In this case a bad bearing will not harm the bicycle nor risk your physical integrity as long as you pay attention, so it worths to play. But it is very different with other components, like a carbon handlebar, that's a risky business, I have heard some really terrorific stories... I mean, China is just an option, usually I will always try to buy good components as long as I can afford it, according to the range of the bike and bearing in mind that I ride just for health and fun, not for money.