I got a $50 CAD regular mat ... it was a mistake. Slides all over the place and it's near impossible to ace even the simplest of the maniac songs (Mr. Wonderful, Kick the Can, 1234 007, those kind of things). Duct taping it might work as previous posters have stated, but it was impractical in my situation.
Not only that, but it breaks easily. If you do get one, don't roll it or fold it to store it (which is weird, cause that's how it came in the box). Something inside there got broken after the second day I bought it, so my left arrow is continuously on and my up arrow only works once in a while
I'm about to buy a metal pad, but I need $$ first :*(