I like when the folders are compatible with other machines. It makes it easier to find what you want. I know cuddlebug folders are compatible with the grand calibur, so perhaps spellbinders will work with the cuttlebug machine. Good luck.
You can use almost all Sizzix dies and embossing folders in the cuttlebug. The only And if you have the 12 inch platform you can use the long border dies. You can also use Quickutz/Lifestyle Crafts dies and embossing folders. You can also use the regular Nestabilities dies. Depending on your die, you just have to use different plates. For example with the Sizzix Bigz dies I use 2 B plates and for the Quickutz/Nestablities I use plates A, B, and C.