The way I look at it is that I'm paying for another cable, or satellite TV. $75 ($65 if you go with 6mo. sub.) is a fair price to pay.

Scrutinizing costs per hour will only make you play less in the long run ^_~

But yah, if you really need to know, I currently play 3 hours a day on average (dual-box). I expect to average probably one more hour per day once I get my 5-box setup.