I asked the owner of Cignot (US vendor) the same thing. She told me that basically you want to find a wholesaler in China and build a relationship with them. If you're not looking for huge lots to begin with, there are some Chinese online retailers that sell very, very cheap; low enough that you could double the price in a brick-and-mortar
shop and still not be completely outrageous on your prices. greenhouseone.com comes to mind.
What is "best" is very subjective; Ego and Riva kits are very popular and well regarded. KR808's are as well, though I don't use them and wouldn't know a knock-off from a genuine one if I saw it. I would suggest starting by looking for genuine Joye products.