There's a quote from 2006 saying that their monthly hosting costs where 15k SEK (2k USD). But also, one of the owners of the hosting company was also the one running the tpb site.
They were not even at the height of their popularity in 2006. And that (very new) hosting company was raided and all 190 of their machines were confiscated, even though only 11 were being used by TPB.
They scaled up a lot from that point too, so that is not an accurate picture of their costs at all.
They scaled up a lot from that point too, so that is not an accurate picture of their costs at all.