RE: About the BD website
Theres no guarantee mate.
All the listing on the BD site means is that at some point the site you're looking at has made a wholesale purchase from BD. Obviously thats better than having no credentials at all, but it certainly doesnt amount to a guarantee that what they're selling, to you, right now, is legit.
Personally Id never buy off the internet unless someone I knew personally (and trusted) could vouch for the site