Congrats to your son that is one sweet card.
The number holds no significance and the value wont increase based on the Dally M or even when we win the comp and Gaz wins the Clive Churchill Medal. As suggested it worth about the $250 mark, Earlier sales were around the $200 mark but as they are scarce and collectors scramble to get one it has increased up to $270 for the last one (crazy St George supporters).
I don't believe it will greatly increase in value but as they are hard to come by and being from one of the more popular sides collected it should, unlike most of the esp cards, hold its value.
Cheers
Ross