Since nobody has answered, I'll toss in my 2 cents.
As a general rule of thumb, I would never get any herbs (especially any that can be taken in lieu of a drug) off of eBay. No offense to eBay or sellers on eBay (as I sell many things on eBay myself)... but there are a lot of people that try to take advantage of eBay and scam a lot of people. Sometimes it's as simple as sellers not sending the items, but most of the time, you just can't verify the quality, source, or authenticity of the herb you're buying and it's hard to verify without expensive testing.
If you buy enough (like if you're reselling it), I would look for wholesalers that you can verify with the Better Business Bureau to make sure they are legit.
I've never taken this product myself (no need for potentially habit-forming psychoactive products), but that's my general guidelines that I would use when looking for any products, especially herbs that are popular at the time. Good luck!
Personal research in my role as a Product Specialist for a vitamin company