So my 5 1/2yo saved up $15, $.25 at a time, which was the amount I told her she needed to chip in for a new iPad after hers (my old 1st gen) died last fall.
We were having trouble with her putting the iPad down for things like dinner, so it was good to have her without it a while.
I bought one of those Toca games, Toca Pet Life, partly because I wanted something without in-app purchases and have always wondered what they are. It seems like just a big interactive world. She loves it so far.
I also got her the PBS Kids games app. That is all free games.