It depends what you're using it for. I was a registered PSuser at Photoshopusers.com which was helpful...however I use PS mainly for digital scrapbooking so I ended up buying Cassie's tutorials which were more "scrapbooking specific". I wished I would have found Cassie's tutorials sooner as with PSusers I learned a lot of photo manipulation which I don't really use.
Also, whenever I teach someone to use photoshop or digital scrapbooking I make them buy CJ's "getting started with templates" (as I think it pushes a newbie quicker into the experience) and I just sit there while they do it and answer any questions or help out when needed. The best way to learn is to just jump in and do it
Good luck with your venture.
BTW the best part of the tutorials is that Cassie is always on the forums with answers to any questions.