I live in the burbs and keeping an eye on the apartment complex dumpsters has paid off handsomely. In my complex, I found a 2014 iMac 27" with a bullet hole through it (never change, Texas). It yeilded up RAM, the optical drive, 1Tb HDD and the case screws.
Look around a few days after Christmas, as that's usually when casual computer users get new rigs and more often than not just toss their old stuff.