Free driftwood is in your local woods go and get some lol. Try to find Oak wood preferably the core of a branch as this takes alot less time to clean and sterilize, but takes a while to get water logged so. To sterilize boil water and dump it on it like 20 times in a bath tub for soaking, scrub with 1:10 ratio os bleach water solution, put it in the oven at a little over 140 degrees as this is the point in which most bacteria and fungi die and you won't burn your wood, pressure wash it to get debri and crap off. You should be fine as long as the wood isn't live or contains sap.