I get a lot of crap at yard sales, thrift stores, etc. Eventually the stuff makes its way into projects. Got some of those NHT transducers out of some toy cardboard guitar amplifiers. Used one of them to make a lunchbox into a speaker, it sounds a little tinny... Got a LCD backup mirror with a broken mirror for $10, nice source of a backup camera (with range marks) and a 4.3" LCD. $10 later and I've got a touch panel to go with it, I plan to attach them to my R-Pi soon.
Outside I've made a table for my (yard-sale acquired) lathe out of pallets and I made a 4x8 table saw by making a wooden frame for a portable jobsite table saw I got for ten bucks missing the extending fences and whatnot but with the pusher.
I don't depend on this stuff for livelihood, it's just a hobby, but you can live better on the trash in this country than you can on normal wages in some others. There's just valuable shit going to hell everywhere. If you could line up end-to-end all the cars that people would have liked to fix up which have been parked in people's yard and just rusted away, they'd probably reach across the country.