I have come across a great solution for this.
GitHub Pages allows you to host your own website as such, as a sub-domain or custom domain, like myapp.github.io or myapp.com all completely free of charge. You can then purchase a domain from somewhere like NameCheap for around €7 - €9 (per annum). GitHub then allows you to connect this domain for free, and they’ll even provide you with an SSL certificate too, all at no cost.
Of course you can’t run the next big Ebay or Amazon style website from here, but for people who want or need a website for their app, this is a fantastic low cost solution.
Note: You’ll need a bit of knowledge of Git and basic web development to efficiently push updates to your website. I recommend checking out EJ Media on YouTube. I’ve learned a lot from these tutorials and can now create basic websites (that look pretty good) for my future apps.