Here in Michigan, we can get a personalized license plate for $35 above the regular registration fee and then to keep it, it costs $15 extra every year. So long as no one else in the state has what you want, you can get most anything on it (except profanity). Each state has a limit on the spaces you can use. Ours is 7. Sounds like you have to buy them off of other people that have what you want? If that's the case, I guess you pay on how badly you want it? That would suck, because everyone would think they have the cat's ***, and want a fortune!
Or is it different than that?