Pretty good stuff there. The top one's the Obsidian Order, but I don't know the one below it.
The problem is, since you're bypassing the company, you also bypass tech support. If you want, or have questions, there are a zillion add-ons (brushes, filters, actions, yada, yada... for download out there.
I Kinda put a kink in Gimp because I found the resources for it at deviant art, and now I have something like 700 brushes, but once they're loaded, it still works fine.
Since you're downloading something with no support, you also have no protection from script kiddies, hackers, and other bad hats in general. It's possible you might have luck in getting juarez (the Mexican version) that work, but them's the chances you take.
Your best bet would be to find some forums dedicated to what you're looking for. Granted, the legitimate groups (those that shelled out for it) will give you a very cold shoulder (banning would just be the start) won't help with questions like this (I've seen what they do with requests like that... but if you ask general questions, and don't reveal your source, you might get some help.