Welcome archshooter.
There are quite a few on line places that carry good leather. Moscow Hide and Fur comes to mind but I know there are a bunch of others. Partly it depends on what kind of leather you want. For tooling, vegetable tanned I think is the norm. Latigo leather is super quality but also more expensive. You might check your local phone book. You might have a shop around home you don't even know about and it's nice to be able to walk in and handle the pieces before you buy. Plus, most shops will have what they call "blems", "seconds" and scrap leather and you can often get a pretty good deal on them.
There are a lot of options though besides store bought leather. I've seen some real nice back quivers made out of the sleeves off both leather and wool coats. You have to put something in the bottom to prevent the arrows from poking through but the soft design conforms to your back and is very quiet and stable.
Good luck in your search.