Welcome to the best information hub on smokers/cookers anywhere!
I use what I can get my hands on, most of the time I get truckloads of free oak, usually more than I can use in a while. I typically run smokes at least twice a month, always have a reason to have friends over for a Sunday game and beer.. :o)
To be honest, I have several resources for wood at really cheap prices, may times free. First place I go to is a tree trimming company my boys occasionally work for. Tree trimming companies have to get rid of the wood they cut. Many times, they take it to the dump, which means they have to pay to get rid of it. This is where the magic happens. I tell them if they have the wood type and size profile I need, they usually respond with a confirmation they will have what I need available. I then let them dump a stack on my driveway every so often and I split it myself and rack it. I have two 8-ft wood racks in my back yard and cycle in wet wood while burning the seasoned wood so I always have a supply ready to smoke with. FREE WOOD ROCKS! For my smaller electric smoker (when I need near total hands-free or just really small batch cooks), I have a barrel trash can that I keep my small smoking chunks in. When I need to fill this, I rent a small splitter and spend a day just making small chunks for this smoker.
On facebook, there are groups like yard sale groups and man cave groups, may times tree trimming companies offer a free drop off of wood to your driveway if you're close to a job, this way they don't have to pay to take it to the dump, unless of course they take it home and split it themselves and sell it on Craigslist or something similar. Be careful though. Sometimes they cut these monster oak trees and dump huge wood pucks that are so big, you cannot split without renting a jumbo splitter and they're usually really really hard wood. Many times, those large chunks do not burn as well as the logs up to 12" or 14" in diameter, properly split. I won't take the huge pucks anmore, unless I am doing a big fire for the boy scout camping trips (I was a leader for 10 years) At that cost/time to split the huge pucks, just buy a truckload of pre-split wood for $100 from someone on CL. It usually costs me about $50 to $75 for a splitter rental anyway, depending on which size i have to get. Second thing to be careful of: If they're dumping free wood in your yard, do not leave it there for days. You don't want moldy wood and I have seen where the termites find the wood within a week or two and start eating it. If it is too close to your house, when you remove the food source, they look for another one. You don't want that food source to end up being your house!
Hope this helps. Good luck!