I have a number of mats that I store in an artist portfolio. These come in a number of sizes and have a handle for hanging. You can get nylon ones and also really inexpensive ones they call 'Red Wallet.' Below are two sites that have examples of the ones I am talking about.
The first has the nylon ones 2/3 to 3/4 down on the page. They are called C Art Voyage Portfolio's. The large 27 x 34 is $36.99. The extra large 34 x 42 is $43.99.
http://www.discountart.com/store/art-portfolio.html
Here are the 'Red Wallet' ones.
http://www.artsupply.com/portfolio/paperportfolio.htm
A C Moore has both the nylon and red wallet in their stores and you can then, of course, use their weekly coupons.
If you don't have a place to hang them, you can also get two of the foam core boards (also at A C Moore) and put them in the portfolio and then place the cutting board between them. These just add a little more support to keep them from warping or bending.