There is so much free stuff out there that I figure I'll wait until I've gotten all I can from no-cost classes before I put out money for one. Here's an example of a YouTube session I really learned from:
https://www.youtube.com/watch?v=33N5X1GqzFw
Once you get there you can see lots more links to other quilty stuff. I could spend all day on these and on QB and links. I think if there was a specific topic I thought I needed I would consider buying a class, but mostly I'd rather buy a yard of good fabric with the same money.