It is free to become a member/register as a vendor and create your store.  There are no fees to list your products.  RD2RD charges a service fee each time a product is sold.  Basic (free) members pay 35% service fee.  Premium members pay 20%.  Stated another way, with a premium membership, your earnings are 80% of each sale (for basic memberships, earnings are 65%).  A premium membership is optional, and is $49/year.