The document discusses the cost of developing a Flutter application in 2021, highlighting Flutter's efficiency as a cross-platform framework that allows developers to create apps for both Android and iOS using a single codebase. It outlines factors influencing development costs, such as development time, complexity of features, and geographic location of developers, emphasizing Flutter's cost-effectiveness due to quicker development and testing times. The estimated cost for developing a Flutter app ranges from $2500 upwards, depending on the app's features and complexity.