My suggestion for evaluation would be to ask the following questions:
-Is the person teaching the course successful and making a living doing the thing they want to teach?
-Is there viable [can you trace it back to an actual person] feedback from other VAs who have taken the courses and are now making money using the learned skills?
-How long has the person been teaching/been in business?
I used to say that I would be hard pressed to find a course I'd pay for - simply because there is so much free information out there and great books at an affordable price. But self-study isn't for everyone and I've come to the conclusion that there are some really great educational opportunities for VAs out there. For example, check the boards for threads on VA Classroom, you'll find LOTS of positive feedback about them.
If there's a course you're considering taking and want to know what others have thought, post a new thread about it and get some feedback. Peer evaluation is the BEST way to get a real perspective on value for cost and long-term application of skills learned in a course.
Good luck!