Cheapest place to get a new set of 15" gradient wheel centre caps?

[Batmobile]

All four were nicked off the car, I've been looking on eBay and people are selling them at £10 each! Is there no cheaper place to get them.
​Thanks
This is an example: http://www.ebay.co.uk/itm/Clio-2-2001-2005-ALLOY-WHEEL-CENTRE-CAP-/320843076269?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item4ab3bcd2ad