A good general dubbing is just regular hares ear dubbing in various colors, or hares ear plus (the plus has a bit of sparkle to it)
The ice dubbing is great for certain stuff, but for more traditional flies, which i guess you guys will be tying at the classes, hares ear is fine.
Awesome possum is good too, a bit softer than hares ear, with longer guard hairs, it will give a more buggy look to your flies.
Basically, any soft natural fur is good for dubbing, as you can see from the species the dubbing in the various kits are from.
The boxes are a pretty good deal as you'll have to tie a lot of flies to run out of one color.
Look around your local fly shops too. I came across awesome possum packets for .87c each in my local so i bought up 7 or 8 colors. You can never have enough fly tying materials in my opinion.
Hope this helps.