I am on a bowling league and once a week I pay $17.50 to bowl 3 games which take about 90 minutes. That's $70 a month for 6 hours of "entertainment" or $11.66 an hour.

If I 5-box WoW (I only 3 box) I'd need to spend more than 6 hours a month enjoying it to cost less than my bowling league.

Needless to say I get more than 6 hours of enjoyment out of it PER WEEK so it's totally worth it for me and my entertainment budget.