Banggood is like, or wants to be, China's Amazon. I personally have not ordered anything from there, but RCers have been getting their "goods" there for years. AliExpress has evolved a bit. Just read/research a bit on "About AliExpress". I tried Alibaba.com (owner of AliExpress) for a large bulk purchase of o-rings. I got very little responses from sellers there, and I got turned off.