Where to find limbs for my snake to climb on?

I'd love to put an appropriate limb in my aquarium for my python to climb on, but the driftwood at the pet shop is SO expensive. I imagine that just any kind of tree branch won't work due to rotting and parasite issues. I guess the saltwater kills off any organisms that want to hitch a ride in the wood, and any wood that can survive seawater won't rot when it's dried out. Does anyone have any suggestions for where to find some good wood?

See about ordering some driftwood from ebay, just get the size dimensions first. I'd then bake it in the oven for awhile. Maybe somebody else can chime in with how long and the temp.