I think there are strange games played in the selling of registration numbers. I have a "COB" registration on my AC Cobra and if I look at a large number of registration sale sites, a good number of them show that my number is for sale. Which it isn't.
I assume if anyone showed an interest in my registration the dealer would be on the phone trying to buy it from me. If I had more time, I should try and buy my registration and see what happens.