That sounds like an easy fix by taking it apart. When I had my 1.2, the central locking stopped working after I dropped the key. Just took it apart; the little click/switch inside had come away from the little motherboard or whatever you'd call it, so just chiseled away at the plastic of the switch a bit and soldered it back to the motherboard, worked a treat thereafter; re-attached it much more thoroughly than renault did.
Deffo wouldn't be paying for a new key, or any alternative, given the fix is so easy.