I have heard that there are numerous black market sources for both ephed and sass in China, despite the restrictions. I have heard this from people who actually live in China and are Chinese so I take my source with a higher degree of credibility. Apparently, poor ephedra farmers will body pack small quantities through the various provinces, as each province has it's own border checks, where it is sold on the coast at a much higher price than inland. Also, if one is caught, Chinese police are just as corrupt as every other poor country. And yes, most of China is poor.
If you talk to enough chinese people, you will likely find someone with a relative back in China that knows someone who does this. It is about as easy as buying cocaine in a night club around here from what I am told by my chinese friends.
But acquiring Sass or Ephed in China is NOT REALLY the obstacle here. Getting it into the U.S. of A is the PRIMARY obstacle. BY FAR!