Raspberry Pi has always been the cheapest of computers since it came into production, but they have broken the cheap barrier with this new model.
The current smallest Pi (Model A+) costs around the $15 mark, which had it as the cheapest SBC, which has put computing in the hands of millions which cannot afford to buy a pc, and powered tinkerers home made projects. But Eben, the father of the Pi, could not stop there and made a version for $5 USD.