There are a few BB websites which have open classified forums. The sources and or UG Labs who advertise on these sites must first gain permission to do so from the board admin, and generally must pay a fee, so they are some what "prescreened" for legitimacy.
The great majority of sources who do advertise on these sites are legit. A scammer get's blasted fast so there isn't much dollar insentive to scam people. Of course good sources can and sometimes do eventualy go bad. The sources with the best products, prices, and service get bumped up heavily by the board members who have delt with them. There is so much competition today that the legit sources are forced to bend over backwards to please the customers.
The government making steroids illegal has actually made buying quality low cost Anabolic Androgenic Steroids (AAS) easier than ever. This makes you wonder if people in government aren't profiting the most from the sale of AAS.