International markets are in play here...
Guys, China is still snatching up all the copper they can get their hands on, for electric generation & transfer, and for electronics. As the Third World gets, and wants, more electricity, and more electronics, this trend is just going to continue.
Brass is mostly copper. Ammunition cases are made of brass. Bullet jackets are also of a copper content.
I scrounge up everything I can lay my hands on, at the range. All the surplus .223 and .308 that the AR shooters discard, all the .45, .40. and 9mm from WWB on the pistol range. All the magnum cases that the rich guys buy as ammo, shoot, and toss. And everything else except the steel and aluminum cases. (Steel on a worldwide scale is still too cheap to bother with, unless you have several tons all at once. There isn't enough aluminum @ my range to be worth the sorting.) Leave the range cleaner than when I came.
The stuff I can use to reload, I save. The magnum stuff I can sell as once-fired brass, I save and advertise. Really oddball cases I save for a collector friend. Everything else goes to brass scrap. I've even started saving spent primers (shotgun are steel; don't bother, but pistol and rifle are all-brass.) My last trip to the salvage yard they paid $1.65/lb. for fired brass.
No use whining, I can't stop the demand, so I might as well profit by it.