Color 3D printing does exist; I got to see some examples about a year ago while visiting an office that had such a printer. They were able to take models from video games and print them, in color. They had some 8-10 inch high figures created in this way, mostly as a test. They looked really good in a cartoony style.
The printer mixes dyes into the plastic powder where appropriate; the color goes down about 1/32 of an inch into the figure.
They were more resilient than I expected but you still had to be careful holding them- small details were often cracked and there were chips everywhere after a few weeks of people like me manhandling them.
I didn't get a cost breakdown as it was just a curiosity at the time, but I gather that while the expense is greater, the time cost is even more so- each color is effectively a separate material which the machine needs to mix and layer on.