HID are expensive end of story. Everything in a Prius is overcomplicated compared to a Corolla for example. It is just a “risk” of owning one of these cars. Fortunately they have turned out pretty reliable otherwise. Be gracious.
I still do not get the whole idea of a Prius except maybe bragging rights for MPG or the newest technical gadget.
Why should they, they’re Toyota after all, no problems EVER occur with them(atleast if you read some of the posts about Toyota’s customer service). Their execs are probably trying to cover this up like they did with some other things. 
I do hope things work out for you in this though.
A qualified dealer or mechanic should charge no more than 1-Hour labor to replace a headlight.
Or, with just a Phillips head screwdriver, one can do it on their own. The HID Headlight is held in by 3-Screws. The top one is easy and already exposed.
The inside screw is exposed by removing the 6-Fasteners that are the hold downs for the top of the front grille, under the hood.
The outside screw is the more difficult to reach. The front bumper screws must be unscrewed from underneath the the bumper and then the front bumper side is pulled out at the wheel well, exposing the 3rd HID Headlight hold down screw.
You don’t even need to remove the headlight, just tilt it up from the rear and expose the HID Headlight cover. The headlight cover is removed by turning the cover from the Closed Mark to the Open Mark and then carefully prying up the cover. Then, remove the HID connector which will expose 2-Clips, holding the HID Headlight in place.
Just lift out the old HID Bulb by the base and replace it with the new one. NEVER Touch the HID Bulb, just hold it at the base and the replacement is easy to complete.
Finally, purchase the HID Replacement Bulbs online if you want to save money. I last purchased (2) HID Bulbs @ $103.00 that INCLUDED the shipping! My local dealer would have charged me $175.00/Bulb or $350.00 for the PAIR.
My original 2005 Toyota Prius HID Bulbs last over 5-Years. Even though only one needed replacement, I decided to replace both at the same time and keep the good, old one, as a spare.