Free tiers usually only give you a paltry amount of egress bandwidth, like 1GB. This site is serving 6,000,000 hits a day, according to the author. At 2.8kB/hit, its using a little under 17GB/day. Still, that shouldn't cost $2000/year - one would think serving a couple hundred hits/second of static, easily cached data could be done with something like lightsail for $10/month or less.