No extra cost as such, unless it's something that spells a rude word & someone might take offence to it
Alternatively, in relationship to a f**tball club, & a rival 'fan' takes exception & wallops your car with a few bricks.
It might be considered inflammatory????
The other aspect you might wish to enquire about is what happens to the registration mark in question if the car is stolen/wrecked/declared uneconomicallyviable to repair.
I keep meaning to ask about that myself