This is the approach I took. If the developer offered an adds free app I would gladly pay for it not to have to deal with "Daddy, the iPad is broken." only to find that Safari had launched and taken her away from her game.
Now that she is old enough to read and some of the game apps she has used her money to buy prompt her to upgrade I just tell her we don't do in app upgrades and she is very adept at dismissing the prompts. Fwiw - Toca Boca apps are great. I still see her playing them occasionally although in the past few months her interest in digital games has really fallen off and she wants to play some of the board games or hide-and-seek instead.
Now that she is old enough to read and some of the game apps she has used her money to buy prompt her to upgrade I just tell her we don't do in app upgrades and she is very adept at dismissing the prompts. Fwiw - Toca Boca apps are great. I still see her playing them occasionally although in the past few months her interest in digital games has really fallen off and she wants to play some of the board games or hide-and-seek instead.