Here's a nice project:
This is the same mill that I have sitting here on my desk. $350 for the mill, maybe $300 for electronics, call it, generously, $100 for extruder hardware. Free, open source software. That's under $800 in materials for something they want $3000 for.
Someone who was inclined to spend a few evenings putting together and tuning up such a device could probably easily clear $1000 selling it on ebay, assuming there are people who would pay $2000 for such a thing.
Most of the hard work is done, for example:
It's mostly and assembly and integration task.
DK