Economic Recovery Through Responsible Homeownership Act of 2008 - Amends the Internal Revenue Code to allow an individual taxpayer a refundable tax credit for the purchase in 2009 or 2010 of a residence located in the United States if the construction of such residence began before 2010 and the taxpayer makes a downpayment of at least 10% of the purchase price. Limits the amount of such credit to $5,000 ($10,000 if the downpayment is at least 15% of the purchase price).