One time At a garage sale I found a box filled to the brim with recorded casettes of 90s alternative bands(Nirvana,Pearl Jam,Green Day). I didn't get them though. They probably have old radio station bumpers/commercials on them.
Ed:An Apple A Day Keeps The Bus Driver Away!
Check out my Youtube page.Full of classic commercials from the 80s,90s,and 00s.
I've gotten lucky a few times. My last big find was an older lady selling her sons big bin of NES stuff. I bought it for 40/50 dollars. It had a Top Loader NES which was worth 80 bucks alone, a SNES and a ton of games for both consoles. I ended up selling most of it though.