Well, I know for a fact that Greyschool is not worth it till you've gone and bought and read the Grimoire for the Apprentice Wizard, and prob best to get the Companion as well. This is because a lot of the courses on GS refer to these books as well as many other reading materials. Plus for the cost, its almost a bit better to learn things on your own first before trying their 7 yr plan(granted its no longer actually 7yrs, but thats besides the pt).
Another one you could check out would be Witchschool.com. Its an ok site with lots of information on all sorts of topics.