on the 206 the central locking motors and closing catches are 1 unit and it is known for them to stop working.
I have never known them to need new looms although i have known the need to modify the wiring with new connectors (some garages may not know you can buy the new connectors although if it is a dealership then the should).
the price is about right if it is a dealership you have taken it to. or if some other garage if they are fitting complete looms then its probably right.