I have two rotary cutters, one of which has a ribbon attached to the end indicating that it is a dull (to fabric) blade, but perfectly fine for other uses (paper, etc.). The ribbon keeps me from grabbing the wrong one.
Then, when the fabric blade begins to dull, I switch the ribbon and replace the now really dull blade. The dull blade gets wrapped in a piece of paper, then wrapped in a sheet of paper towel and taped around the several paper layers before going in the trash.
I like the idea of resharpening, but postage rates, etc. come to almost what new blades do through either Harbor Freight or J. Hittle, so I'd rather go with the new.