Unless he's really, really mature for his age, get him a 97-03 GT, not a GTP.
Tell him if he goes a year in even a GT without a speeding ticket or accident you'll help him drop a GTP engine in it.
And 2,500 isn't really a "good deal", that's about right for that car.
But, like I said, if you think he's ready for a car that quick already...go 97-03 GTP.