A simple answer to your questions is that you need to research, research and research the suppliers of salvia.
I can say it in one word but its not that easy one supplier who is having a good reputation at one time and in one state has no reputation some time later. There are many suppliers using flashy banners on the net which don't even have any accreditation over selling salvia divinorum.
I'm not a frequent salvia user 
but my friends are 
and more luckily many of my neighbours are taking salvia divinorum not as an addicitive but for a spiritual desire or some other meditations as many people say (I really dont know what exactly is that thing is) .
Almost 80% of them are buying from Potent Salvia Divinorum seller and as far as i know some are purchasing from a vendor called Fresh Salvia . Only those who travel frequently manage to get salvia divinorum from mazatec garden (Exactly where potent salvia gets its salvia from) That is why people love to buy from potent salvia and they also ship to you smoothly without any potent loss.
