I believe this is the Chinese version of Amazon. I ordered some hair extensions for my daughter from two different places and they arrived fine. If you check the shipping, you'll see it is International.
Edit: I found some websites with more info. Aliexpress is the retail side of Alibaba (the Chinese eBay).
http://searchingpanda.com/aliexpress-reviews
http://www.techmesto.com/aliexpress-tips-stay-safe/
Basically you need to exercise the same cautions you would use if purchasing from eBay. The prices are so good because many of the items are coming directly from manufacturers and companies in China.