Udemy is currently offering many $10 courses. I received an email for a course that was $39 when I last checked it out. The email linked me directly to that specific class with the $10 offer. There doesn't seem to be a good way to search their website for a list of these deals, so you may need a coupon code from 'retailmenot' or some other site. But it appears right now hundreds of them are on sale until April 20th. There are also numerous free courses.