I have an opportunity to get a 24 x 36 OLFA cutting mat for 28 bucks, but is it the one I really want? It is self-healing, but only one-sided. Green with yellow markings. Some have block-sized grid lines which I think might be nice. Other brands? - 3 times Joann's has been out, only having Dritz - with no price and I didn't have the stomach to stand in line to find out. What mat do you use? It's like I'm frozen and can't buy any of them.