With template sites like Squarespace or Wix, you can create a mobile responsive website by yourself with a couple days' effort. App creation is more complicated, especially if you want the kind of functionality and user experience that will really get your customers excited.The cost of building an app depends on the features you want and whether your app will be for Android, IOS, or both. But you are likely to spend a minimum of $10,000, and a fully-featured app can cost well over $100,000.