My mate has one which he's got by chance on an old Laguna. He's not even an Albion fan and wasn't aware of it until I pointed it out. I'll let him know he's sitting on a (very minor) gold-mine.
On a more mundane note, how do you go about getting just a standard number plate with the letters BHA in it? Is it just a question of buying the car in a certain geographic location? I've seen a few about, obviously belonging to Albion supporters.