Couldn't this just be a variation on the classic loss leader sales strategy? It also reminds me of what Amazon originally* did, get someone to sign up for an account, buy a widget at or around cost, ship for free, and then make the money back on the more expensive larger items as you become the "go to" for whatever someone needs.

*I say originally, as my experience with Amazon has been on a downward trend for at least the last two years.