Although costs are discussed, electricity consumption is not, and it can be very significant as shown below. Consumption is very dependent on how much the printer is used and the annual TEC (typical energy consumption) figures below are based on printing for 1 hour per day, five days per week for 52 weeks per year on a typical UK electricity tariff. Where possible, figures come directly from http://www.sust-it.net/ .
Brother HL-2035: £37.05
Canon i-Sensys LBP3010: £11.85
Dell 1130: £6.31 - £9.44? (No Dell devices listed on SUST-IT; first figure from Dell literature, 0.78kWh per week; second from US ENERGY STAR, 1.3kWh per week at 230V)
Epson Aculaser M1200: ?? (No figure in Epsom literature and no Epsom devices listed on SUST-IT, ENERGY STAR sites)
HP LaserJet P1102w: ?? (No figure in HP literature though ENERGY STAR compliance claimed; this device not listed on SUST-IT; US ENERGY STAR consumption figures blank)
Samsung ML-1665: £7.26 (No figure in Samsung literature; not listed on SUST-IT; this from US ENERGY STAR, 1.0kWh per week at 230V)