There is a Cydia “tweak” that lets you get in app purchases for free! Obviously you need to Jailbreak your iOS device to use this.
I’ve tested this with Jetpack Joyride, ComicGlass and Robot Unicorn Attack 2 and it worked very well. It did not work with Futurama, or PokemonSuffle.
This Cydia tweak is called LocallAPStore. You can get it from repo.hackyouriphone.org
So in Cydia, go to your Sources tab and press Edit in the upper right corner, then press Add in the upper left corner. Type in repo.hackyouriphone.org and press OK. Now use the Search tab option and search for LocallApStore and install it!
Now to use this tweak, you need to open your iOS Settings. Scroll down to LocallAPStore on the left side if you’re using an iPad and select it. Toggle the Enable setting. You are now ready to use it!
Open the game you want to purchase something in, and press to purchase something for real world money. After it pops up for your password, PRESS CANCEL! Do not type in your password or it really will charge you! After you press cancel, it will successfully “purchase” that item.
If you would like to continue this guide and install paid applications for free, check out this post!