It's unusual for an iPhone app to cost more than few bucks, but with hundreds of thousands of apps available, and the convenience of iTunes billing, it's easy to sink a fortune. Thankfully, some developers have found a way to cover that cost with advertising, others belong to the open source software movement, and some are even motivated by the kindness of their hearts.
https://mhapks.com/download-penfed-apk-for-android/