I've used quite a lot of the bits from China in various 2/3/4 flute types, end and ball, upcut, etc. To my surprise, even though they were very, very cheap, they have actually been as good a value as any others I've bought from other countries. I do buy the better of the cheap ones from sellers I trust, but for an example I'm still getting 20 x 6mm 2 flute HSS endmills for around $30 shipped! Hard to beat that value. And I'm still on the first one of many of that type I bought, thinking they wouldn't last long before they broke or went blunt!
As another mentioned, the length can vary between sets or batches, but they have been diameter spec the few times I've checked them.
I have no hesitation buying any of them, from the better and reliable sellers that is of course. No doubt there will be some sellers selling absolute rubbish, but there's quite a lot really good sellers on Ebay. Just always check their feedback, and scrutinise their listings.
cheers,
Ian
It's rumoured that everytime someone buys a TB6560 based board, an engineer cries!