CR Henderson & Sons has a nice selection of Civil War ammo and hardtack boxes, all properly built and stenciled. Although he doesn't have a large selection of everything, what he does have is correct in dimensions, color, and stencil lettering. He also seems to have the spirit of improving the accuracy of his products. I like that.
Apparently, for more complex boxes and desks, he'll work with the customer. That's a nice service in itself.