Luxury home builder Toll Brothers said today that its second-quarter revenue fell 51 percent as banks decreased lending and demand for homes fell. The company’s sales for the three months ending April 30 were $398.3 million, down from $818 million at the same point in 2008. Since 2006, Toll Brothers’ stock has lost more than a third of its value. The value of the company’s unsold inventory also fell 55 percent, to $944.1 million, from last year. The average sale price dropped to $563,000 in the second quarter from $575,000 in the first quarter.