An iPad is pretty portable and has zillions of apps for a dollar. No Adobe Flash, but extremely intuitive and user friendly. Price around $600.
A PS3 gives better graphics and sounds. Not really portable and zillions of games ranging from $5 to $80. Price around $400.
Personally i'd go for an Android 4 Tablet. Preferably with a dual core cpu and an nVidia GPU built in. It's got Adobe Flash and also zillions of apps for a dollar. Slightly less intuitive than an iPad, but nothing a 13-year old can't figure out. Price around $400
If you want to play with Android 4, get the ISO file right here and put it into a Vmware player. Your own free virtual tablet.