RasPi + Cloudflare should be a good solution. Even live streaming is possible with CDN as live streams are just conventions with playlists and metadata. I can't comment on costs at scale, but Twitter claims equal ingress and egress bandwidth for Persicope (ie. first egress hit caches), standard HLS will just have more latency and not more cache misses if I understand correctly. My stream is 1500-2500kbps 720p.