Aspen, I always got at Tractor Supply (TSC) when I used it. Just be sure that you're not buying pine on accident. If not, you could ask a local feed/farm sore to order it for you.. or even a pet store.. I bought a few big bags of vermiculite/perlite at Home Depot a few years ago; I am lucky that I still have some remaining, since I can't seem to find it in any stores lately.

For heating supplies. www.reptilebasics.com has never failed me (Flexwatt, thermostats, etc.)