I only sell them locally in my city period, but yes I am operating from the US. You can try to follow the guide above and build your own, though! Shipping costs would make this much less cost effective, potentially.
I run a small computer repair shop and do some work with local charities, and they get a lot of requests for gaming PCs that they can't fulfill. This is just a solution for that.
I've built 6 so far, kept two for personal use, sold two and gave two away to a local foster care charity. I plan to build 6 every couple of months and give away a third of them. I mark them up to just under $300 when I sell them, so this will allow me to slowly outfit local schools / after school care centers / children's charities with low budget gaming computers for the kids! Reception has been very positive so far, I am very upfront about what the computers are capable of and how they just look like basic office computers.
The $300 price tag still lets budget gamers get their hands on what is probably the cheapest prebuilt gaming machine available, and covers my costs for donating them. And again, this is all local, I live in a pretty small town of only about 100,000.
I don't know what your local market looks like, but probably. The goal is still an i7 6xxx or i5 8xxx or newer. At least 210W PSU, and find a way to 16fb RAM. SSD is absolutely required. RAM and SSD prices have dramatically fallen in the US at least, not sure about worldwide. The Rx 6400 can be bought new on Amazon, Alibaba, or straight from AMD.
Try to find a mid-high end computer which is several years old and upgrade it. Where I am, you absolutely can not build a computer cheaper than buying a slightly outdated one.