I buy regularly from China, the quality is hit and miss, here's how the past year went for me:

1. Bone White ABS - doesnt matter what supplier, this is good stuff. Prints like a dream.
2. Black ABS, doesnt matter who - this is rubbish, have tried 8 brands, its all the same. They use crap to make the black colour, you can even see it if you cut the filament, you see tonnes
of colours and foreign crap.
3. Colours, ie Yellows/Reds/Blues ABS, are good but melt at a low point, the dyes make the prints go goopy if its too hot.

The only downside to buying it is the shipping costs to be honest.