Over a decade ago I used to run a Linux server (Redhat at first and later Gentoo) that did some routing, stored files and hosted my website and a squid proxy. The Internet link was a terrible upload capped cable connection with a dynamic domain name service to update the host name when the IP address changed.
The server was a bit of a beast with 4 hard drives in it so I imagine it would have used some electricity. Using the current electricity rates (0.19c per kwh * 24hrs * 31 days * 0.250kw) I estimate running the server would cost around $35. And that does not factor in the cost of the connection.
Here is the comparison:
Computing power is cheap and virtualisation is making it cheaper.