start with samples. decent place in the US to get samples with reasonable shipping, etc is puershop.com Also www.yunnansourcing.us
has some samples, also in us.
Think of the samples as tuition, and just keep buying new ones until you start to know what to expect based on factory, etc. And don't order whole cakes for a while even if you think you like something, otherwise you are going to waste a lot of money on undrinkable crap.