Couldn’t I buy a 3D printer and then print 3D printers to sell at a cheaper price?
Almost.
Now the cat is out of the bag ...
There will be metal, elastomeric, and PC board parts that can’t (yet) be printed. But yes, printing the 3D printer parts that can be printed is one of the popular things to do with one.
Not really but close.
3d printers don’t really do circuit boards at the moment and they do not do micro chips. However, with modifications to the 3d printer’s head (3d printing with a Dremel tool) it is possible to etch out circuit boards. That requires significant changes to the head end, the existing electronics, the slicing software, etc to switch between the two “modes”.
Given the cost of pre-built electronics vs the time required .... it is just easier to buy for most.
Took me a while to find an article about using printers to print circuit boards. http://www.instructables.com/id/3D-Printing-3D-Print-A-Solderless-Circuit-Board/
This is a different method that using traditional printers to etch circuits. http://www.instructables.com/id/PCB-etching-using-laser-printer/
Here is a picture of the Ultimaker circuit board. http://www.ebay.com/itm/like/121376071237?lpid=82
Note how complex the board is for the cost of $30 to $35. In other words, I could buy the part or spend hours of my time working out the details, finding the right components, printing the board and then solder in the pieces .... or spend $30 ish.
Look up “RepRap”. 3d printer that makes copies of itself.
Sure, you can print braces and similar parts. But the motors to move in three directions and to push the filament into the heated extruder are not printable (in plastic). Those are the expensive items and this guy uses motors from e-scrap. However, the stepper motors are around $20 and you need four or five; the heated extruder (mostly made of metal) is probably under $100. An even better machine is buildable for under $200, but this guy has a decent approach.
Yeah, I got the 3d printing bug.