Our WalMart has some occasionally, we have a couple of farm stores that keep them regularly. If you have none of that, do you have a Sporting Clay range near you? If so, as if you can buy some.
I just remembered that I saw a pallet of bios the last time I was in BassPro, but that's been months ago. Gander also has some but like nearly everything there, is ridiculously expensive.
Whatever you do, don't buy a few cases to be shipped in.