Four things work pretty well for recovering brass.
1) Grandkids. It pretty much only costs you a couple lollipops or a couple pieces of bubble gum but you've got to raise at least one kid first to get 'em. I'm still trying to decide if it was worth the effort just to save brass.
2) A large tarp. Works well if you stand in a small area but if you're moving around a lot working up a sweat then it pretty much falls short of it's intended purpose. I'm not sure I understand all the running around anyway... that's why God invented rifles.
3) The Brass Wizard. Little football shaped wire basket on a broom handle. Roll it along the ground and it picks up everything bigger than a .22. (Some .22's get caught in there, no big deal. Comes with a metal bracket that slips over the side of a plastic bucket. Place the wizard over it, twist, the wire bales spread open and the brass drops into the bucket. Works pretty well except for in deep or soft sand, the cases tend to sink into it instead of getting picked up. I would rate it as being 70% effective in soft sand, 95% plus effective on a harder packed surface or concrete/asphalt.
4) Doggie pooper scooper rake and pan. Get 'em at Wally World, Petsmart, where ever. Short rake with a dustpan on a short pole. Works very well, even in deep sand. No bending down, can be very selective on what you rake up. Will rake in some sand but it's no big deal if you use a shell sorter or media separator... sand just falls into a bucket then toss it out.
Oh, yeah, there is another way to salvage brass that won't break your back;