Affordable, Fast, High Res DLP-SLA 3D Printer

[Feign]

What the heck are in these resins that make them one of the most expensive liquids I have ever seen? Is it some rare and precious mineral in them, or just a total lack of manufacturing secondary to lack of demand?

In short, yes they do, and yes there is.

There is a thread over on the RepRap forums about making your own homebrew SLA resin, but it's dangerous, time consuming, difficult to get a successful batch, requires some chemicals that are controlled and some that are rare. The process gets a bit more reliable if you have actual specialized lab equipment, but in general, under about $80 per kilo is worth your time and safety.
Specialty resins, like conductive and no-ash resins are secret formula kinds of things, so there's no alternative to those costs.

But they compare favorably to ink-jet ink

Everything short of pure precious metals and nuclear fuels compares favorably to ink-jet ink on a price-per-ounce basis.