Need a OBD replacement cover

[Barbossa]

Garage lost my OBD cover, they said it was on when they released the car, and I can't be bothered to argue.

So, been looking on eBay and such, seems ridiculous that they are on for around £10, for what is essentially just a bit of plastic.

Anywhere where I can locate one for a more reasonable price? I'm honestly thinking its value should be no more than a couple of quid, if that.