Just did a search and found Speedpress.com (for those that had the 30 x 36 mat like me, it looks like that was a Dritz/Prym product and I think Olfa took that line over)ANYWAY Speedpress has the green cutting mats with standard sizes but they will also do free custom sizes! Yippee! And they look price competitive. Here's the link:
http://www.speedpress.com/products/2/2