Dealer type Number Plate backing things

Does anyone know of somewhere I can find some plain black number plate backings, like the ones that the dealers fit behind the plates and it sticks out below the plate and says for example... 'Norwich Volkswagen'

I want some plain black ones, so I can get some white lettering cut and make some myself that say something like 'Volkswagen, Sao Paulo, Brazil'

I can find loads of those plastic frame type ones on ebay, but cant for the life of me find just the backing ones that get sandwiched between the plate and the body.

Is this what your looking for

http://cgi.ebay.co.uk/VOLKSWAGEN-Black-Number-Plate-Holder-Frame-Surround-/290475542719?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item43a1b108bf

I've got a couple. The number plate sits in the frame which snaps shut and holds it in place.

I want the simpler ones, that just fit behind the plate and they stick out the bottom, not the full clip in frame jobbies...

Also want them plain so I can add my own writing.

Na just go for a big number plate fills the space better.