East Rock family home, 5 of us in top two floors (~1800 sq ft) pay an average between $500-$600/month in the winter with Apple Oil. Oil prices have more than doubled since we moved in two years ago, the house is poorly insulated, and we're required to keep the house at 55 so it's always set to 55. I think others have given great ideas for why it's so expensive (insulation, temp, use, space, etc).