Develop a Mac Application

i need an app. the purpose of the app is to sell videos. (all the content are original ) the videos will be in different categories. ( about 6 categories ) under each category will have about 4 sub sections then each section will contain about 40 videos. the videos are going to be sold so i want them locked untill he user pays for the videos. each section will feature about 4 free videos an the rest will be locked. Basically i need an app like the bookstore but this one is for video only. i want the app to work on both android and apple. free download and each user creates an account. i live in ghana so i need the developer to come up with easy ways of accepting money for the videos.. scratch card, code etc..