No online Vendor discussion. Wikipedia will answer your question about legalities.
Federal law states that it is unscheduled, however the analogue act allows it to be related with 2CI an schedule 1 drug. Several states have issues their own laws because of stupidity, abuse and the media who has misreported a lot on the popular NBOMe's, calling everything , even 2C style gelcaps 25I NBOMe.
You should be fine as long as you keep you amount small, IMO, there are a handful of US vendors, but they are really simply middlemen, very few are actually doing the chemistry or at least that is what I have been told.
50 mg's of the substance is probably cheaper then you would expect ---. 50 mg's probably won't attract the attention of anyone. BUT you should have access to know how, and have access to a quality scale that goes into the microgram range before you start trying to figure out a dose.
NBOM'e are quite potent and not for anyone who is inexperienced or uneducated. READ READ READ READ, go to the big and dandy threads here, go to Erowid, review the good and the bad..... then research on yourself if you must find out what it is all about