Tandy Leather sometimes has scraps the right size, otherwise you need to buy the whole hide.
But use the yellow pages your area.
Look leather or saddle shops.
We have one in Laramie that will sell by the square foot.
He's 50 miles from me. Tandy is 20, But I go to the guy in Laramie. Buy what I want or need.
I'm opening a BP accessories store next month. Plan on having a hide or two on hand.