crazy_dave: Interestingly I've read that researchers are seriously looking at iPads for autistic children. I too would've thought a large glass screen would be a bad idea, but apparently its just sturdy enough combined with its large touch interface that the parents of some autistic children have noted their autistic child truly engaging with it and it holding up under use. At the moment it's all anecdotal, but I read about a couple of research projects aimed at seeing if iPads were a good fit for autistic children for learning, growth, and entertainment. It could be a really good boon for parents of autistic if true.
Yeah, well even at the cost of an iPad it's inexpensive compared to actual medical equipment designed for special needs children (really this stuff gets insanely priced), but really it's about having something with really good feedback that you can tailor to your child's needs. Now, I know many autistic kids are too wound up by video games to really play them, but for others the feedback loop can be really beneficial, which is why I like DS and DS games (as well as other games) for my daughter.
PCs can be great for these kids too, but the more general purpose interface can be very daunting as well. iPads do fit a niche, I'm just saying a DS is 20% of the price and may help his child in the same way (he knows his kid best). Plus some kids freak out and break stuff, and a iPad is way less rugged.
orcishgamer: You might find a DS Lite to be way more indestructible, though, if that's a concern.
Darling_Jimmy: This case is another option:
http://www.lifeproof.com/lifeproof-store/apple-cases/ipad That could really help with the rugged issue if the the OP's child doesn't have any tactile issues with the material.