I can almost guarantee that number is positive and % Repeat is something they closely monitor and consider in their internal equationss. As any direct response/lead gen marketer knows, customer retention rates/repeat buyer % is a crucial element in the formula. I suspect they have a very clear idea of what this rate is right now, and as their business grows, this number only gets more accurate. Right now, operating costs aside, they only need to get their lifetime value per customer above $5.75 in North America, which isn't entirely unfathomable.