Odds are they're hacked accounts. There are plenty of forums where people sell this sort of thing. I doubt OP is going to directly rip anyone off, but you may have some issues if you transfer funds like this to your account more than once or twice.

Note that you're usually not stealing from the person whose account got hacked - you're stealing from Amazon, because these funds are likely acquired from social engineering Amazon via the hacked account.

You can make your own decisions regarding whether or not you care. I'm definitely not buying, though.