I have yet to see a 3D printer yield anything useful.
Useful is a broad term. 3d Printed stuff can be useful, pointless or it can be junk.
But lets get this straight. this 3d printer is mostly a toy. Granted it can make other toys.
Bottom line, the sum of all the parts of the 3d printing experience make it totally worth $200.
For me, its an entry fee into a hobby that is going to drive me to learn 3d modeling, expand my knowledge of hardware and electronics plus let me print out dollar store trinkets with the occasional useful item thrown in. Printing repair parts is just one example. I've spent more $$ on arcade parts that are just sitting around the garage doing nothing.
As for cost of ownership...time will tell. So far the spool of blue PLA filament cost me $15 and I had the printer running all weekend and have yet to make a dent in the 2.2 Lb roll.
I estimate the car took .15¢ worth of material. (probably less, I am guessing I can print out at least 100 of those little cars, it could easily be more)
The lever doorknob child lock is ~5-10$ on amazon and I printed one out for ~$1.
This is just the beginning. Sure I can buy better versions of most of what I can print out myself...but the fact remains that I am turning a roll of plastic wire into objects. That is Amazing!
And the few times that I need that specific custom plastic part will be all the more sweet!. But really its to make more toys!
As I mentioned I want to print out some Quadcopter parts.
Edit:
Quadcopter examples