Have you seen 1-2 €£$ devices from Ebay? I mean ready to use switchmode regulators, amplifiers and such. A single chip costs more than that. It is hard to believe that the seller gets some profit.
But there are surplus sales somewhere where they build most of electronics we use, maybe they get their parts there. And of course, large manufacturers get their parts at very low cost. 7£$€ is way too much for them, less than 1 is more likely.