It is annoying that the answer is basically "we paid someone [Cloudflare] to do it." In light of that I decided to run some of my own numbers and figure it out. They are pushing about 245 Mbps out of Cloudflare (averaged over the month). Wholesale IP transit prices are anywhere from 10 cents to a dollar per Mbps depending on volume. Cloudflare dumps 40% of their traffic over peering, putting their price at $14.70/mo.…
This would be approximately equivalent in spec to what you could build for $2500 purchase cost if buying a 1U machine and colocating itself.
For 30 bucks a month you'll get something very old and weak.