With leather distributors and tanneries, they often look at anything under 200 square feet as a small order, and won't do a lot to help with it. I have only worked with one company that sends samples, (
Wickett & Craig in Pennysylvania). If you are looking for Horween leather, check out thier
Tannery Row which targets hobbiests. Another supplier I like is
Maverick Leather, who like working with the small hobbists.
When you say you are looking for "Bog Oak" leather, what do you mean? Are you looking for vegetable tanned using oak extracts?