Walmart is stocking a mat similar to the large Elnas, the 24x36" jobs for ~$25 a piece.
I built my cutout table out of two framed 4x8 pieces of cabinet grade 3/4" plywood. Ending with an 8x8 space, elevated on cinder block. High enough to work around but low get on top for doing layout for quilts.
I recommend buying those small mats and sticking them together in whatever size you need, painters tape will hold them together easily. These soft mats don't dull blades as quickly as the big white ones. However, I've found I use the exacto knife or utility knife blades more than rotary, since you can't cut cuben with the rotary blades very well.