Boyfriend possibly buying a used 2011 Prius. What does he need to look out for?

3G prius requires virtually zero maintenance. I haven't been in the 3G prius scene in a while (I have a CT200h) but really the thing that comes to mind is the EGR issue. Make sure the car starts smooth, particularly for cold first starts. Ask the owner to let you drive it first thing in the morning. Do not warm it up before you get there. Make sure it doesn't stumble and shake. Should smoothly start and idle. then ask about oil consumption if the owner has to add any oil. check the oil level.

 

some 2011's burn oil. the egr as mentioned above is an issue for some, usually around 100k.

other things to consider are the inverter recall and subsequent question of failure, and the brake actuator failures.
these are the important things to research.

2011 regular maintenance varies, depending on where you take it. i would pay almost $90. for an oil change every 10k around here, $20. for tire rotations, $50. for brake inspection and lube.
tires run from $60. to $150. depending on what you want. air filter is $20. but a dealer charges $60. for installation. same with cabin filter. diy can save a lot of money.

complete fluid change and spark plugs are around 100-120,000 miles, so look into what has already been done, and what has not.

a car fax would hopefully tell of any accidents, and a dealer inspection of the vehicle would be a good idea.

 

I just bought a 2011 four about 2 months ago (127k miles, 2nd owner). Besides looking for what others above said, go to mytoyota.com, make an account (if you do not have one) and enter the VIN as your own. You will have full maintenance history.
Mine had been faithfully brought in for the first 90k (had inverter recall done, other stuff too).
I also would suggest hooking up an OBDII reader with Dr Prius and check the hybrid battery to see how much life is left in it (mine was at 71%).
I knew brakes/rotors were toast (thought I felt a bad wheel bearing, was correct!) and it had 4 new snow tires on it, so I needed tires as well.

Make sure you consider what the car needs maintenance wise regarding the price. I paid $6500 and about $700 for all the required work needed (labor supplied by me).
I have been VERY HAPPY with my purchase, been getting constant 51-52 MPG.