If you want to start doing bigger projects, then you will have to bite the bullet and realise that leather isn't cheap!
You can get different types of leather but for stiffer workable hide, you need to get veg tanned cow hide.
If you faff on trying cheaper thinner leathers or splits for example, you'll just end up needing to laminate it or line it with something else, so ultimately you spend the same amount as you would have in the first place.
Decide what you want to make, work out how much leather you need then price it up.
sorry if this sounds negative but I've been where you are at the moment and ultimately there's only really one solution.
LePrevo are probably your best bet, you can phone them, tell them what you intend to make and they'll try to help as much as they can.
atb
R.B.