I also collect and process my own leaf litter. Although, as lynn stated, it is inexpensive and i know of a very reliable source in the pac nw if you don't want to go throuhh the through the effort.

90% of hardwoods that are completely dead and dried out will work. I use a lot of oak in my vivs and aquariums. I roast it on low in my bbq for about an hour. But there are numerous ways to treat wood for a viv and they are all effective.