A published report on Sunday computes that it would now take $1.13 million to buy one of each paid app. The most expensive apps on average are those for the business and medical categories, weighing in with an average price of $11.28 and $11.39 respectively. The game category has the lowest average price at $1.69 although that doesn't include in-app purchases.
Another chart shows that the Games category is roughly composed of 50% paid and 50% free apps while another graph shows that the Education, Games, Books, Medical, Business and Reference categories make up about half the expense of buying out the App Store. Of course, if one were to buy each app available, good luck finding enough room on your iPhone to install all of those apps.