I’ve been using Udemy courses. They’re always really cheap because they never stop a sale and it’s always within 90-95% off. That’s about from USD $10-15. See on udemy.com.
Here are some courses I would recommend:
HTML: https://www.udemy.com/learn-html5-course/
CSS (including Sass!): https://www.udemy.com/css-the-complete-guide-incl-flexbox-grid-sass/
JavaScript: https://www.udemy.com/javascript-bootcamp-2016/
Those are some of the basic things for web developing, but here are some nice libraries and frameworks that are really cool:
Angular: https://www.udemy.com/the-complete-guide-to-angular-2/
React: https://www.udemy.com/react-the-complete-guide-incl-redux/
Vue.js: https://www.udemy.com/vuejs-2-the-complete-guide/
jQuery: https://www.udemy.com/jquery-course/
And lastly, a great CSS framework called bootstrap: https://www.udemy.com/bootstrap4-course/
See more on https://academind.com/learn/our-courses/
Hope this helps.