I store all my 8 1/2 x 11 SU cardstock in hanging file folders, in one file cabinet which I got at an office supply store (OfficeMax or Staples). The file cabinet slides under my desk, and I can easily get to it if I need more cardstock.
My 12x12 SU cardstock are stored in a JetMax cube with 12x12 hanging file folders from Michael's.
I don't pre-cut my cardstock either. I keep them in their folders, and just cut what I need.
I hope this helps.