At that age, they tend to be very particular with their related equipment wants... beyond what parents know unless the parents ask. We would either use his friends/girlfriend as secret intel operatives or just ask him for a Christmas list. Or, maybe leave out an Eastbay catalog and see what he zones in on.
One thought... when they are in this deep with baseball, sometimes it's nice to get something totally unrelated to remind them that they are much more than baseball players in your eyes.
Also, if he is already committed, he may appreciate some school logo apparel.
We have no idea what your son already has or doesn't so this is sorta tough. Lessons? J-bands? Workout equipment?