My Boy is 5 and Like yours is very god with looking after things so after stealing his mums all the time we agreed to get him a Camera for his Birthday ( JUNE)
I was looking at all sorts and then seen on Ebay a 6MP HP for under £50
I liked it, as it is extremely easy to use and takes SD cards (cheap)
Have the fixed lens means less battery drain and less likely to break. the lens is tiny, but some of the shots he has taken are truly fantastic ( well I would say that

)
I can post some if you want
Any just looked on ebay and
THIS ONE looks almost identical to it.
HTH
Doug