Marketing
According to Fiksu research, it can rake up $200,000 in ad expenses to push an app into the US top 25 iOS app ranks. Canada is a bit cheaper at $15,000. In Germany, top app ranks can easily cost $65,000 in advertising expensive; $45,000 in the UK, $30,000 in France, $35,000 in Brazil and $10,000 in Thailand.
Meaning I would need at least $260k+ to get the app into the top 25 iOS apps section in North America and the United Kingdom. This means that I need over $300k to get this app to succeed in a sense, this is quite a daunting number which could in part be funded by a crowd sourcing campaign like Kickstarter or Indiegogo which would help but also it would need backing from a developer who could put money into the project.