C.O.
Leap Pads aren't impossible - they are just expensive now...
http://www.ebay.com/sch/i.html?_from=R40&_trksid=p546...
I would NOT give a 4 year old a 3D DS....I regret buying the one we did - in fact my boys didn't like it and traded it in at gamestop.
There are some games out there for limited reading but I am sorry - I can't remember which ones. I can do some searching...