Any recommendations or insights?

Looking at getting our DS (10 yrs old 4th grader) a tablet or e-reader. We have been thinking of this for a long time and thought it would be a great summer gift. Our original plan was just to get a cheaper one since it would mainly be for fun and entertainment. But since we just got the Dx of reading disability and ADHD-I, I want to make sure the one we pick out can provide more than just fun. So any suggestions are welcomed. I want to keep it under $300 (cheaper than that is of course better!) and one that has a good insurance policy (DS is accident prone wink )

I have read on a few sites that e-readers/tablets are very helpful and puts a little fun (and holds the attention) in reading and such. Since we were already thinking about one- figure why the heck not (unless there is good evidence against it)

Thanks
Cory