How much would a cover to go over the gear linkage on a P Reg Renault Clio RL Versailles cost?

It appears to be plastic, l think it is the gear linkage that it covers - when l move what it covers the gear stick inside the car moves.
Sorry, Forgot to say it is under the engine, around the middle.

Where exactly in the car does this part live?

There is usually a plastic cover under the gear linkage pivot under the gear lever, but the linkage is then exposed between there & the gearbox.