I'm thinking about an amway type model, where users sign up new customers and get a small percentage of their initial purchase price (less than the Best Buy margin) and an even smaller one of sales to the lower tier. You can also have a small payment share on the yearly premium service plan.
The only way a person makes money is if they sign up a lot of new customers. Who in turn sign up a lot more and so on.
I know they are announcing a referral program, I hope it has a multi-level marketing spin.