Any pet store should have it...maybe even Wal-mart. Just look in the rodent section. There are usually lots of bags of wood chips and stuff like that. I buy the aspen that comes in compressed packages. It's like a square log and I just chip off what I need and crumple it up into loose aspen shavings for my snake.
If there is anything the nonconformist hates worse than a conformist, it's another nonconformist who doesn't conform to the prevailing standard of nonconformity.