The recycling bin for paper is always overflowing in the printer room at our office. What that means is that there's perfectly good blank sheets of paper...that can pretty easily be turned into this cool crafted notebook.
While printing double-sided is the way to go, in the mean time, over at Instructables, there's a great how-to on making a recycled composition book. The whole process takes about 45 minutes and all you need is a hole-punch! Get the details here.