Brass from shooters is getting hard to find since most of the folks are getting into reloading. I had the same problem with 340 Weatherby brass. If you Gioogle 264 Winchester you will find quite a few places that sell it and you can decide if it is in your price range.
Critter, Most places are on backorder for new 264 brass, I have a couple thousand rounds loaded but our prairie dog season is close so it won't last long. anyway I'm still looking for GOOD used brass if anyone has some they want to sell.
I cleaned out my local Sportsmans Warehouse when it was shutting down. But now that I think about it, I remember there being some at the Loveland store last week. If you're still looking, I can hook you up, assuming it's still there. PM me if you need it.
Bring them in on a string. I love this term, if you want to be successful on calling in Elk, try not to just sound like the other caller. We all laugh at each other when we are practicing Elk calling at home or while camping. When I first started calling in Elk, I had no idea what i was doing and it's funny how many I could call in. The biggest Bull that I have called in to date was actually my first. I was making cow calls and screwing it up big time. But it's obvious I didn't screw up...