The cost to create a ReactJS app depends on your needs and what you want to achieve. The more complex the project is, the higher the costs are. So, from the start, you should decide whether you need a simple app or something more complex.
Some common cases that require a more complex solution include: advanced interactions with both web and mobile devices,
real - time data updates,
dynamic content,
and personalized user experience - these would require more time and effort from developers than,
say,
creating a static website. < br >
For deciding on the cost of the ReactJS app,
contacting with experienced ReactJS web development company is the best way to get consultations.