Welcome to the Quilting Board!
I found some laminated folders at the office supply that ended up being about 40 cents each. They are light weight but seem to work well with my1 yard cuts. This would be a good time of year to check out the sales.
Check to see what size will fit on your shelves. I had to buy comic book boards that were 10 1/2 x 7 1/2 so they would fit on my bookshelves.
Remember, people will see your quilts long after you are gone....NOT your housework!
I used coroplast and wrapped my fabric in fourths, so my boards are 11.75 by 8" so they fit a standard bookcase (that I get from Wal-Mart for $30.00). I use smaller pieces for my fat quarters and even use odd pieces for strips and bindings. Here is a picture:
Mine are 9X10 because that fits my bookcase. It leaves a piece that is 3" X 20 which could be cut and used for something, I suppose. However, this is what they are used for:
So many quilts, so little time.
I like the idea of cutting them to fit the shelves they'll go on--just makes sense. Measure the height from the top of one shelf to the bottom of the one above it. Then measure the depth of the shelf to get a width. Don't forget to subtract a few inches off the height so it will easily go on the shelf. Good luck!!!
I measured the height and width of my fabric cabinet then cut my boards to fit. I cut the boards in half for my fat quarters. This method worked perfect for me.