Cheap Leap Frog Diji

I am a big proponent of shopping for Christmas early! I was doing some searching on Amazon and found some Leap frog Diji games for under 5 dollars! That is an excellent price! Now we dont have a leapfrog Diji, but the system is on sale too. Do any of you have one? I am really wondering if it is age appropriate for my almost 4year old. Advice anyone?