Visit Shershah market with some one who knows the place.
There you will find complete door inside panels (powered) for Corolla. You can also trade you old door panels with the powered ones.
You will just need to change the door panels and connect the wiring, which can be done by any good electrician.
The cost will depend on the availability. Negotiation is the technique to get a good deal.
i would recommend to use JDM stuff if u want conversion
i did in my friend indus bought it for shershah complete setup which include motor , switchs ,door lock ,central locking ,door trims costed 15500 and installed it from water pump charge 3500