It does cost $$ to join the BBB.
As a business owner I have been approached twice by the BBB with an "invitation" to join. They as much as said "Would you like to pay us to join, so we can say good things about you". Their other line was "We have been getting inquiries about your business, wouldn't you like to join so we can say good things about your establishment?"
That does not sound unbiased to me!!
Hmmm, let's see, if I pay them $600 a year they will say nice things about me, they will plug my business rather than someone who does not belong to the BBB.
With that experience, my view of the BBB changed for good. It is an advertising business operating under the veil of being some kind of consumer protection agency.