There's someone selling for 20$ here. They're afterall a "get to know btc" kit.

Not everyone is prepared to run an electrical monster like the S1 24/7 and pay 30$ monthly to cover expenses.
Not everyone has 400$ to spend for the S1 or 3599 for the S2.
Not everyone is mining for the sake of finance.

I think the purpose is to have you mine to 0.01 btc. Electricity should be negligible to folks who never shut down their PC. When BTC hits 40k$ like winklevosses said it will become a perfect introduction. If btc tanks to 0 you have a pretty usb accessory, a balance to look at in your PC. You will only lost 20$ afterall.