Welcome to bachido!
There are only 3 parts that make a shamisen right handed or left. The kamigoma, the azuma sawari, and the koma. The koma can be installed backward since it is made to be removable. So that’s not an issue.
The shamibuddy is right or left. And it is more affordable.
Kamigoma under all three strings and you make your own sawari. Kyle Abbott has a video on how to do this with a shamibuddy.
They are currently sold out like many things are right now but it is the least expensive and easiest left handed beginner shamisen I’m aware of.