MA is pretty rigid on what they call "vanity" plates. It initially costs $50 to apply for the plates. Then it can only have a max of 6 characters/numbers, characters first then numbers second and no mixing them up. There is an annual fee of $100 every November to keep the registration of the vanity plates current.
"Special" plates; example, Red Sox, Celtics, Patriots, Cape Cod, Save the Whale, etc., and YOM plates follow the same rules but require re-registration cost of $100 every 2 years. YOM plates have to be original with no re-paints.