I was at Home Depot a couple weeks ago. They had a lot of 2x4, 2x6, plywood, 4x4, landscape timbers. I had a whole flat cart full. I found the lumber mgr. It added up to $25. I asked him if
I could get a better deal on all of it. I got it all for $12!
I also drive slowly on trash nights. I got a large Igloo dog house someone was throwing out. You can find all kinds of good stuff on trash nights. Doors, windows, fence.
Check dumpsters at construction sites and behind shopping centers!
Pallets are a great source of wood. Some people even recycle the nails. Some people drill out the nail heads. I use a saws all to separate mine.
See if there is a recycled building store near you. I get hinges there for 25 cents! I got a 12' 2x8 for a roof beam for $7. 20"x20" vent covers for $1. Doors (without frames) are $10 and windows are as low as $2. Mine is called Construction Junction.
Check Craigslist daily.
You have a couple months. You should be able to find a lot of stuff.
Good luck.