As a #38 witness with @blockbrothers, we have 2 witness servers and seed node and it costs around 800-1000 STEEM a month at current STEEM price.

We are around break even at these STEEM prices.

With MIRA coming out the server costs should come down because it reduces the RAM costs.

A top 20 witness makes 110,000 STEEM a year.

We have some additional costs with other servers for Steemify and other stuff. But that's besides what's needed to be a witness.