I got the free earbuds too and I thought they'd at least be decent quality since the brand seemed legit. It turned out to be a rather disappointing. The packaging it came it has no sign of a brandname whatsoever. It was just a little black plastic container.
What does a site like that stand to gain?
Information? Not like identity-stealing type of information, more like consumer statistical data. With lowered prices, people are more willing to splurge on cheap items like these. Corporations would still like to see what people would really spend their money on, even for the most of penny-pinchers.