I joined the Better Business Bureau OnLine a couple of years ago. You have to also be a member of your local chapter. Cost me under $500. Then I split test some sales pages where the only difference was having the BBB logo on the page or not. And sales increased significantly on the pages with the logo. Enough to pay for my membership in a couple of weeks.
You need to be registered in business with your state for at least a year. Depending on your business, they may even check references. In my case, they asked for references of people who bought my products, and even people who asked for a refund. It’s good to know they check this out before they admit you.
The system also sends an email to you every time a visitor clicks on the BBB logo to verify your status. I get dozens every day so I know people are checking it out.
The reason it works so well is obvious. BBB is one of the few logos that is recognized by almost everyone, and seeing it gives people a better feeling that they can trust you. You can’t overemphasize the importance of trust when doing business online. Visit the Better Business Bureau for more info on joining.