I think the Mass RMV has a plate checker as well. But still, one of the reasons I want to move up to NH is the fact that the fee for personalized plates is minimal, down here it's like 70 bucks per year. They make you pay for having a low number plate now too.
I got an old low number plate for my car, I need to check with the registry to see if anyone else has used it under the YOM law as an antique plate yet.