Where do you get your laser supplies?

Submitted to Ask the Makers

I've got the Dremel LC40 laser cutter, and I've been loving it so far! Unfortunately, it's proven to be difficult for me to find materials for it, in particular, wood. I put some regular wood from a local shop in the machine and it involved about 3 hours of re-lasering it to make a full cut. I asked Dremel support and they mostly just said to look for "laserable" wood, but I've had no luck outside of the Dremel materials library! I'm all for using Dremel's shop, but I'd love to have more of a variety of options (they only have 2 kinds of wood). Any suggestions?