Sunsei SE-1200 Solar 18-Watt 12-Volt Charger for $99.99 plus $5 shipping, which comes to a total of $104.99 shipped.  This solar panel can potentially replace the daily power consumption of 12-volt lighting systems and appliances.  Here is a screenshot for your reference.  It usually sells for $155.  You may also be interested in the 2009 tax credit related to implementing energy saving devices at home here.