I bought some ayahuasca once. As long as the company is based in the U.S., you have nothing to worry about.
how do you not have anything to worry about? what if they take your money and ignore you? what are you going to do call the cops?
Use your head and find a respectable looking ethnobotanical supplier. You should know what the big ones are (I don't think you're allowed to name them in this forum). People order this shit all the time. Usually you can tell if its a scam when they make alot of noise about "legal highs" and shit like that. The ones that claim to be selling it for nonrecreational purposes (though I can't imagine what those would be) seem to be more legit. If you want to know which company I ordered from, send me a PM.
