I hadn't even decided on getting my new car when - as a 50th birthday present - my wife (with a little help from the rest of the family) bought me a plate with - her initial + 50 + my initials. As it was a surprise I don't know what she paid for it but it was held by Motor Marks who have been very good.
Unfortunately it's cheaper to buy one and not fit it to a car, but I think (as long as you don't have to commit an offence by altering the spacing etc) it's a good anti-snob touch. You aren't showing off how new your car is even when it is.