I think it's fine.
The value of the damage is the official price to fix. Using a heimish guy is no different than choosing not to fix it all.
I dont think its fine.
I have hear or read once that If you do not plan of fixing it, they (the one that made the damage) is only חייב to pay the deprecated value.
Hence value of damage is really depreciated value not cost of repair.
Same would be if you totaled his car, you are not responsible to pay for the cost of repair if its more than the value of his car.
I would say, same would be if you are able to fix it in a cheaper place.
I do not know Halacha, and would recommend to ask a Posek