It's money out of thin air to offset the expense.
It's not coming out of thin air. The money to pay for the iTunes transactions is coming from the "lump sum" in your iTunes account. The current amount of this "lump sum" should be listed as an asset. If you put more money into this "lump sum" amount, you should record that as a debit to wherever the money comes from and a credit to your iTunes account. When you make an iTunes transaction, you should record that as a debit to your iTunes account and a credit to wherever your money went to in iTunes. If this doesn't answer your question, then you should make your question clearer, because I'm not sure what the issue is.
You've commented that you are paying for business expenses out of a personal iTunes account. Best practices would be to have a separate iTunes account for business expenses. As it is now, you're paying for business expenses with a personal account, and your confusion as to how to do the accounting is a manifestation of this mixing of funds. The reason there's money coming out of "thin air" is that your personal money is bleeding into your business without proper accounting.
If you insist on having only one iTunes account, you should at the very least create a "virtual" account. Every time you pay for a business expense with your iTunes account, debit this virtual account. This will of course accrue an increasingly large negative balance. This represents the fact that every payment you make from your personal iTunes account to pay for a business expense creates a debt that your business owes to you as a person. One way to handle this would be to put money into your actual iTunes account from a business account, debit that account, and credit your virtual business iTunes account. By doing this, your business is paying you as a person back, and so the debt (represented by the negative balance of your virtual iTunes account) decreases.
Depending on the structure of your business, you may be able to create an "owner equity contribution" account. You as a person can put money into that account, either by "forgiving" the debt that your business owes the actual iTunes account, or by putting money into your actual iTunes account from your personal fund and recording it as a deposit into your virtual iTunes account. Both of these actions amount to you explicitly investing your personal money into the business, and should be treated a equity contributions. Again, this does depend on the structure of your business, so you'll have to look at what rules on equity contributions apply to your particular case.