Advantages of using the MERN stack for web development are -

JavaScript Everywhere:The MERN stack uses JavaScript on both the client and server sides, allowing for efficient development and understanding of the codebase.

React's Virtual DOM:React utilizes a virtual DOM that makes the application fast and efficient.

JSON Support:MongoDB, a NoSQL database in the MERN stack, uses JSON-like documents for data representation.

Large Community:The MERN stack has a large and active community, which means better support and more resources for developers.

The timeline for building a web application using the MERN stack can vary widely based on the complexity of the application, the number of features, and the proficiency of the development team. A simple application might take a few weeks, while a complex one might take several months or more.

An example of a web application built using the MERN stack by ThoughtWin IT Solutions is "Gettaxshield." This application utilized Angular.js for rendering pages and performing API actions, Node.js for storing data from the Call Tracking Metrics server onto the Firebase database, and React.js for generating data stored on the Call Tracking Metrics website.

The cost of building a web application using the MERN stack can vary significantly depending on the complexity of the application, the number of features, and the rates of the developers. It's hard to provide a precise cost without specific information about a particular project. For an accurate quote, you need to contact the development team with details about your project.