Plastic notebook covers!

[Neurosylum]

Hi again guys! I was just wondering if anyone knows of where to buy flexible plastic that they use to cover spiral notebooks. I wanted to make a mini index card for classes (with my own designs!) and I don't know where to start looking. I was about to use clear shrinky dink papers, but they're 8"x10" and the cards I'm printing are on regular 8.5"x11" cardstock, so the cutter I'm using will result in uneven dimensions.

Pleeeeeeaaase, if you have any idea what I'm talking about (I'm not crazy, honest!), I'd love to hear!

Thank you!