Curious, where do you live that there isn't a craft store near by? There are 1/2 a dozen in my little town and they all sell the plastic canvas for making ATS screens with, although the first time I went looking I spent a good 1/2 hour walking through the store until I finally spotted them on a bottom shelf tucked away. They only cost 33cents each though.
I can't see how using any type of acrylic would work as good as the screen material. I just can't see how you could rough up acrylic enough to work well. Even a wire wheel on a drill wouldn't do it and that is about the best idea I can think of to rough up acrylic.