I have not heard much about the costs of repair except for one guy where his prius needed some little controller that cost several thousand dollars, and he was told it is a fairly common repair.
Now, with the newer vehicles coming out that are getting 30-40- and even 50 mpg, the payback period will increase and possibly to the point that it is not financially beneficial to even buy a hybrid or electric.
My next door neighbor has a hybrid SUV
He has worked in the car business & even owned his own shop years ago
They had an electrical problem & it took him 8 months to get the vehicle fixed
It went to several dealerships & many skilled mechanics that he knew tried to resolve the issue
At present I will not buy one, we did look at them
It was easier to reduce gas use/cost by having multiple people commute to work together
Plus I combine trips when going out & we do errands/shopping together
That shaved over 20,000 miles a year off our use
It has been my experience that many in the automotive repair field are not very good at electrical troubleshooting.
I've had people come to me and almost beg me to fix electrical problems on vehicles which the mechanics could not fix. (Because they have seen me fix these problems on my own vehicles which is fun for me.)
So if you understand computers, know how to use a multimeter, can read wiring diagrams, understand electrical circuits, and good at relay circuit troubleshooting, LOTS of opportunity in that area now.
A good book on the future of vehicle computer systems/networks and electronic gizmos is by Bosch "Automotive Electrics Automotive Electronics" (New vehicles can have 3 computer networks, and 24 to 80 different computers!)