sad to hear that, and i can feel your pain cus the same thing happened with me 5 days back outside alfatah lahore. the damn guy took the left side mirror of my corolla altis and i was not the only victim, they also took one side mirror from 05 civic , 2 side mirrors of 09 corolla gli, 2 side mirrors of 2007 2.0d saloon.
later on i complained to the alfatah authorities because nowhere in there parking its written "parking at owners risk".
these guys were very nice they took me to the cctv room and we examined the cctv footage which showed 2 people on a bike stealing all the side mirrors of cars in a duration of 5 mins and 40 secs during rush hour. i just missed them by 5 sec and they left.
they also tried to take the mirror of a prado which was of the owner of alfatah but some how they failed.
i asked about the price from toyota walton motors lahore, they also said its very common these days.
08 corolla (power side mirror) : Rs 3100
09 corolla (all 09 models have power mirrors with integrated indicators) : Rs. 4100
best of luck!