This is how it works:

1. Buy a bra from Onestopplus.com to become a member
2. Buy 5 more bras within the next year
3. Get a free 7th bra (anything up to $30) paying for the $1.99 shipping

More information about the Bra Club.

It is not such a bad deal actually, It can be seen as a $5 discount on each bra you get .