$500 seems awfully cheap for a 3D printer. I know they've been getting cheaper lately, but I don't think a $500 one could be very good.
We have a printer at work. I use it to make prototypes. As a prototype fabricator, it's pretty decent. It produces parts quickly and at reasonable tolerances. The parts it produces, however, are
ugly. The material is really soft, and the surface of the plastic looks very dull. The texture doesn't feel very good on your fingers. The parts will
melt if you leave them sitting in sunlight. I've never tried painting anything I've made on the printer.
At a certain point, you have to ask yourself what you get for $500. It sounds to me like the value proposition of your game is that you get a machine that will make minis that are uglier than the minis that you could buy for cheaper.
From the name "Endless Hordes" the impression I get is that you plan for players to build up huge armies on these printers, so that the cost of the $500 printer could be spread out over a huge number of minis that they'd make, but the resin that these printers use isn't cheap, either. What's the cost-per-mini of the resin?
If you are going to use a 3D printer, why stick to the fixed minis model? Why not take advantage of the fact that it can produce any kind of geometry and let users design their own models? You could give users software to modify "base" units by giving them special features and armor and weapons and poses and whatever they want, and then generate the mesh for the printer. That way, users would really be designing their own units, which would be a distinct advantage over minis games.
Why even stick to a 3D printer? You could sell papercraft models that print out on conventional printers. Full-color card stock space ships would be cheaper and look better than anything coming out of a $500 3D printer.
If you're married to the idea of users making their own minis, there are cheaper ways to do it than with a 3D printer. Example:
http://www.amazon.com/Creepy-Crawler-18643-Bug-Maker/dp/B00499UKKS