Fred,
I can't/won't make a rifle for someone else for less than $6000. That is for a plain, fully brass mounted, right-hand flint rifle with a moderately curly red maple stock. Most of my iron mounted guns (my particular niche) are mid-$6000s. A carved and engraved rifle is going to be mid-$8000s. Those prices are no indication of how good I think I am. They are the prices I must charge in order to make a living where I live. They also represent an opportunity cost; in other words, the price I must get in order to build a rifle as opposed to doing something else for a living. I am fortunate in that I can and have done a number of things for a living. If I make a gun for less this this, then it is by definition, a hobby.
Again, these prices have nothing to do with artistic merit or craftsmanship. I am well aware there are a lot of people who do better work than me, and most of them lurk here. The prices I quoted are purely about economic reality. It takes so many hours to build a rifle, and I need to make so much an hour in order to pay my bills. Other's circumstances may be different; meaning that their economics are different. However, from what I can gather, these prices are in line with what the real professional builders charge.
I am not sure if you are asking what it would cost to make an as new rifle like the Kiser or a similar rifle that looks like an antique. I only know two or three contemporary builders who could make a new rifle of the decorative level of the Kiser rifle and make it look like an actual antique. I believe they would charge five figures for such a rifle. Although, they would do a better job
While I feel the rifle in question has artistic merit, I feel the craftsmanship is not up to the level of the best work being done today. Actually, I know at least a half dozen builders who would make you a better rifle of the same artistic level for less than $10,000. Some would charge more, but a good number would do it for less.
I have answered your question fully and frankly. I hope I don't end up regretting it.