technologically a 9 yo should totally be on it
i was playing chess at 8 and coding on my zx81 at 9-10 (damn who remembers there early teens spending all weekend typing in pages of code from a magazine only to find one of the last lines was smudged lol)
the value of the item on the other hand is a different matter, i had one of the first digital watches at my school (red led casio) and within a week i had taken it to bits and reassembled it.
i guess there's a balance between exposing them to as much technology as soon as possible so that they learn from it and turning them into a potential spoilt paris hilton wannabe