Andrew,

David's advice is good.

If you have time for mail order, you could get the leather supply catalogue from Weaver Leather in Mount Hope, Ohio. They can send you practically any sort of leather you want, in whatever thicknesses.

Essentially leather comes in two finishes - chrome tanned and vegetable tanned. Most furniture, clothing, bag, etc leather is chrome tanned; most saddlery leather is veggie (chrome tanned has a shinier chemical look about it). The two types handle and feel differently - play around with both - and each has its own particular qualities to recommend it according to the job.

Best of luck