I've used Alibaba with good and bad experiences. I used them as a source to get one of my initial HID suppliers, and the company I dealt with was decent - although not great. I did quite a bit of research into the companies I dealt with, and was still fairly let down by the quality of the samples, so I didn't go any further with those mfg's in that niche.
Now, are you ready to laugh?? Keep reading
I then decided to play a gamble and bought a Nintendo Wii on there. What I ended up getting was a "Vii" -- and it was an 8-bit poorly built plastic box with a wired remote and a cartridge of 2 games. WOW it was ridiculous. Needless to say, that wasnt a great experience.
I think you're taking a fairly big risk by playing middleman between a company in China (or Indonesia, etc) and a business or entity here. Unless you're getting samples well in advance so you can QC, you're 100% certain of the company you're dealing with, and all the stars align - I think you'll be okay. But it only takes one very big hiccup on a large order to bring the house down.