Well, there is no fixed cost for this. certain factors and features can decide the cost of the development.
However, if you're looking to build your own blockchain like Polkadot. The method you prefer to build plays an important role here.
Building from scratch can be wise because you can integrate the essential things that your business demands according to your wish with the advanced technologies incorporated into it. Also, can purchase a pre-made script that contains the essential things needed in the blockchain, and you can also enhance the features and functionalities accordingly.
Building a blockchain like Polkadot from scratch can be time-consuming as everything needs to be initiated from the basics. But, purchasing a clone script can save a lot of time as they are a pre-made software that holds all the needed features into it.
So the methods and other factors determine the cost of developing a blockchain network like Polkadot. Likewise, Choosing the best Custom Blockchain Development Company is also needed to be focus. Look at their previous works, reviews, client feedback, and portfolios before you discuss your ideas with them. If all these things satisfy your business ideas and financial support, then you're in the right place for your business development.