The biggest threat to vendors is the same threat that plagues all real world drug distribution networks. The biggest lie is that LE only works up the chain and isn't interested in anyone down the chain. That's only true at the lowest level, for dealers who sell personal amounts to end clients. But if you're a dealer distributing large quantities and your source gets busted, LE is likely to be interested in you as well. SR vendors need to be aware of and take precautions against these traditional real world threats as well as all the new threats and challenges that come with selling anonymously online.