The model sold for $1800. It does not look like any of the models I am familiar with, and if it is a one off, it easily required much more than 100 hours to complete. The details and quality of work look like a first rate job.
I am a modeler more than a full size cannon fan. I find it easier to make and own things that can be carried in one hand. I have a small home shop and make model engines, steam and IC, as well as cannnon and whatever else strikes my fancy.
Here are three of my efforts;

My larger, beater, Fourth of July and New Years salute cannon is outside in the snow. I also have a couple of larger naval guns coming to completion as time permits.