Store your files in backblaze then proxy them through some cheap vps (to cover bandwidth) and add local cache through something like nginx so you're not going to the source frequently.
Some hints: ovh is good for eu/(northern) us (loadbalancing ip + vps behind it to spread load - be prepared to ditch vps if you're getting horrible performance), scaleway if you can live with just eu
Probably as cheap as it gets from big providers
Obviously going to have to compromise (round robin dns > ~1gbps, self managed stuff), but thats just expected
If it's just images probably just go with cloudflare
I'm not asking for advice I'm stating it does technically complicate your setup. What if two people request overlapping ranges concurrently etc... it is more moving parts to setup, test and administer
Obviously going to have to compromise (round robin dns > ~1gbps, self managed stuff), but thats just expected If it's just images probably just go with cloudflare