My idea was to push for some type of software that could customize a plan for a 3D printer. Like how most video games have a character design portion to customize your avatar only instead of a bunch of pixels it gives you a CAD drawing of some type.

Just to point out, their website states that 1 liter of the resin those machines use will cost 150 USD.

Which is about 0.15 USD per medium sized mini.

That machine looks pretty good. What gives me confidence is the fact that they actually put a reference on their pictures, so you know how big the models actually are. The tractor example could be any size, and obviously on a bigger model you see the ridges much less.

I don't think the miniature manufacturers should worry too much, though. Resin mini's only cost a couple of dollar each, and don't require a machine. By the time 3D printers reach the "good miniature quality for less than 500 USD"-mark, the intelligent miniature manufacturers should already be selling customisable 3D designs for download.

If you use PLA resin (there's a pure form and a blended form - go for the blended form), it's relatively cheap and can make some amazing models. Not sure about paint retention though.

That's why miniature manufacturers will be able to sell miniature grade resin with better paint retention