That doesn't surprise me the least bit about the driftwood collector, but remember this is a FLOWER industry. A lot of these items are intended for use for display purposes ONLY, often times landscaping.
That's the biggest risk you have to take if you're buying materials from the FD to add to your aquarium in an attempt to save money. As with anything, examine the item you want to purchase CAREFULLY to make sure it wasn't treated with any toxic chemicals/preservatives.
Someone else in the NY section mentioned they paid $3/lb for petrified wood @ a local fish shop, not sure which one it was though.. If you figure out which shop, mention it here & check to see if they have more pieces in the back. Also if you can take some pictures of the stack, I'd appreciate it.
Next time you see the driftwood guy, take a picture. That's what I'll do if I see him.