King's X has the right of it--lots and lots of self-help on here and I'm sure someone nearby will pop in soon.
I have a few ideas for you based on what I can find locally and my experiences.
Co-op Extension Service Agents, especially the liaisons for 4-H and FFA, and the local Boy Scout Council/Troop Leaders might be able to put you in touch with leatherworkers that teach the youth in your area. You might be able to find someone who'd be willing to teach in exchange for help at some of the youth classes and camps. Fair warning though--Be prepared for various levels of chaos if you go this route. Chaos and kids go hand-in-hand and the more kids, the more the chaos! (From personal experiences, I would avoid anything that would involve teaching those under 11 or 12 years old and teaching groups of youth larger than 5 or 6 youth per instructor. I also recommend a parent or other adult for every 5 or 6 kids under the age of about 15. Kids under 11 tend to get bored to quickly, while more than 6 at a time means a lot of horse play and not much actually paying attention.)
Feed and Ranch Supply houses are also good places to wander into and talk to the owners and customers. Especially the Mom-and-Pop types. You'll know you have the right spot when you find the folks who make their own tack, wallets, and boots, or know who does make the stuff. Feed and Ranch stores are also great place to get things like saddle soaps, leather conditioners, and cleaners (lexol, lexol non-darkening, neatsfoot oil, etc.) if you don't have access to a leather store. Shipping costs on liquids can be a bear (no pun intended), so I buy the big bottles at the ranch supply down the street.
Find the people with horses and you'll find the people with tack--and those who repair it, make it, and sell it. Talk to the DVMs, farriers, and blacksmiths. Find the local equestrians groups--they usually have a newsletter that sometimes lists classes that can be attended by the public.
Horse shows, county and state fairs, ren faires, rendezvous (aka mountain man jamborees), rodeos...I seem to recall that Maine has Cavalry Reenactors? Reenactors, especially of the Civil War and Revolutionary War have makers that supply their gear or they make their own. While at these events, find a maker and see if they offer classes or would be willing to trade some instruction for some help. Ask about short-term "apprenticeships"--they teach, and you help with the work--watch the local labor regs on this though. Some regs require that a wage be paid and taxes collected, some don't as long as no money changes hands. (Several jewelers I know have done this to learn some of the more obscure techniques and the instructors are happy to have the help. Most of them don't mind teaching either, as each person tends to have their own style and will take what they learn and go their own direction with it, so direct competition with similar products is a fairly rare occurrence.)