I've been doing woodwork for a long time, and get most of my wood from used single-size bed frames on Gumtree/Marketplace. People effectively throw the beds out

I've been doing woodwork for a long time, and get most of my wood from used single-size bed frames on Gumtree/Marketplace. People effectively throw the beds out (or at most want AUD$20-50 for the entire thing), and they're generally made of some pretty decent wood, especially the older ones.