Well, there's Backblaze B2, it would only cost $0.10 per download: https://www.backblaze.com/b2/cloud-storage.html

Alternatively, there's bittorrent, which was pretty much designed for this.

But considered you can find decently priced dedicated servers with unmetered gigabit ports, seems like installing Linux + nginx and enabling automatic security updates might still be the best option.