I personally refuse to buy driftwood unless it is JUST the piece I was looking for. It's far more fun to find it on your own, and it's FREE :D There's not much that goes into making it aquarium safe other than sanitizing it which can be done in boiling water, in the oven, or chemically with REALLY diluted bleach. Then all there is to do is sink it which can be done in your tank or in a water holding item of some sort. You might even be able to get lucky and find some driftwood that is already water logged if you take a rake when you go looking and rake the edges of the water ways. In my tank I only have one piece of driftwood I bought, and that was because it had some AWESOME algae growing on it that I wanted to harvest and put on my other driftwood lol.
This is my tank with my naturally harvested driftwood:

only the little piece with the algae was bought.