One very interesting resource, albeit on that is a bit of an anachronism for the "exact" period you cite, are the reproductions of the old Sears catalogs that are available here and there. I've seen reproduction 1897 and 1906 catalogs. Each has very complete ammunition and accessory descriptions and prices, and has a large number of guns available. As this was at the end of the transition from BP to Smokeless, there is a strange mix of new and old... including Luger pistols right next to muzzle loading muskets in the 1906 one. Most of the late 1800's guns were still being offered at this time, as well as what we now recognize as the beginning of the modern gun era.
Highly recommended for hours of entertainment, and not just in the gun section.
Every farm apparently needed a pound of cocaine... for $2.00