Nearly 80% of the more than 3000 apps in the iPad app store is paid. Only 599(20%) of the apps are free. In terms of the breakdown between the type of apps:
Games still is the clear winner : 942(804 of these 942 are paid apps and 138 being free)
Books apps : 154(mostly paid, which is not surprising at all)
Mobclix says the average price of apps is $4.99; and it will cost $12,572.78 to buy all the apps that the store offers.