A little over 500k is still about 500k more than what her first album didHer album sold 1 million because amazon sold it for 99 cents the first two days of release. Without that she would have only sold a little over 500k 1st week.
.And that logic is not reasonable, she would've done a lot more than 500k if amazon wasn't selling it. Cause some (or a lot) of those people who rushed to amazon to buy it would've probably bought it through official channels if the amazon deal didn't exist. It's pretty reasonable to assume that it was her crazy teenage fans that got their moms to register at amazon to be able to purchase it.
Her album sold 1 million because amazon sold it for 99 cents the first two days of release. Without that she would have only sold a little over 500k 1st week.