to my knowledge, prime applies to everything -- and it's a huge success. piperjaffray reports there are about 2 million Prime users worldwide and a 20% increase in spending on Amazon after users sign up for Prime.

2m users x $79 per year = $158 million by the way. huge. and that's just revenue from the subscription service, not including the average order increase. plus a 92% renewal rate.

re: amazon stores -- third-party amazon stores offer a great deal for retailers who want to backfill their inventory with products they don't actually carry. amazon then pays the retailer affiliate fees, and the buyer doesn't know the difference.