I would love to audit it but I lack both the time and knowledge. How would I verify that what I've audited is the source for the actual binary that the App Store delivers to my phone?
You can compile and deploy the app yourself onto your devices with a free developer account. If the one-inch wall around the garden is too high, then maybe the garden isn't a place for you.
A free developer account and a Mac, since only a Mac will run the compiler and the code signer. Inch and a half, maybe, especially as I gather OS X virtualization is much improved since they started giving the OS away free.
I would love to audit it but I lack both the time and knowledge. How would I verify that what I've audited is the source for the actual binary that the App Store delivers to my phone?