There's always 'Python 3.3 for iOS' which is $3 or 'Pythoni3.3' which is free.

This would be absolutely awesome, as for IAPs, I'm absolutely repulsed by them. A single 10$ fee would be much better. But I think it should also be noted that there are also free python 2.7 interpreters for iOS that run locally but are inferior in quality(I'm thinking about pythoni2.7 by XiaoWen Huang, which includes tons of useless crap unrelated to python such as deeply philosophical works in chinese, a flashlight, a password manager, a web browser, a voice recorder, a calculator, and a tutorial for python).