Do things at home, definitely!
"2 months below age" is pretty meaningless. That's average, and that's fine. It might work as a pinch point for learning, as speed does for my DS7, but it's not a real problem if you keep in mind that he can't help his speed, that it's real and not just dawdling. It's more of an area to keep in mind and a weakness to fiddle with briefly but often. Probably your DS is going to be a "deep, but not fast kid," just like mine. It makes grade skips harder, since they work at the speed of a kid their own age but think like a kid older. <shrug> Otherwise, no real trial except to your patience.
But I wouldn't spend $3000 for working on speed, unless you needed that higher processing speed for some specific reason (program, planned grade skip, etc.) No way!
