they look cool, I like them
I will say that being such a limited market there is little chance you can properly reimburse yourself for your time in. Those carriages must take a lot of time to make.
Does a grand even come close to paying for your time? I get the hobby thing, but if you go and start selling them you might end up spending more time on making cannons than would be worth your time.
Ever made a 1/3 or 1/2 scale one? That would be cool and real fun to shoot.