If they take your money for a product, then they are professionals for handling consumer cases, they are obliged to be.
They might not want to be, in which case they should hire people who do want to be.
It is not about what you do, it is how you do it, and in particular what expectations you set.
If you sell it like a regular product, without saying clearly up front that it is not supported, then people will legitimately not like you.
IF you are just selling a kit without support, SAY SO. Then the people you want will come buy it, and if you did well on the parts that you claim to do well, you'd have happy customers (modulo the few Kens & Karens who expect everything for nothing).