The person who laughed at you for being left-handed (?!) is very unprofessional (and, that's just bizarre).
I am sure that one of the main problems is the very small size of guitar that you are wanting. Many luthiers will not have experience with such a small guitar, and as a result, they will not have the proper equipment or set-up in their shops to make one. Perhaps you are not aware of all that goes into building a guitar, but it is a combination of very precise components, measured, cut, and set up to very precise standards, and trying to make a tiny guitar, for luthiers who usually only make standard sized ones, will require an entirely new set of measurements, components, etc.. That will add to the cost, because it will take them more time to prepare and build it.
You wouldn't be simply commissioning a custom guitar, you'd be commissioning a custom-custom guitar -- something very much out of the ordinary. And, if a luthier has never built such a small guitar, they may not even be comfortable with the idea, because they may not know if it would be up to the level of their standard guitars.
That being said, there are undoubtedly luthiers who would be up to the task, and who may even regularly make smaller scale instruments (left or right handed), but you just need to do more homework and find them. But don't expect it to come cheap.
If the cost is prohibitive, then, again, something like a Kenny Hill 615 might be worth more of a look.