Below you can find a few links to master various CS, SQL and data science skills from scratch and for free or at very low prices.
https://www.dataquest.io/
https://onemonth.com/
http://datamonkey.pro/
https://www.codecademy.com/
https://www.udacity.com/
https://www.dataquest.io/
https://onemonth.com/
http://datamonkey.pro/
https://www.codecademy.com/
https://www.udacity.com/
