NEW YORK (REUTERS).- One of the most valuable private art collections ever offered at auction, led by an $80 million Picasso, will be sold in May in a sign that the art market might soon flirt with the record levels seen before the financial crisis struck in 2008. The sale of more than 50 works at Christie’s from the estate of Mrs. Sidney Brody, a Los Angeles philanthropist who died in November, is conservatively estimated to sell for more than $150 million. It is one of two prestigious collections being handled by Christie’s. The other collection includes 100 works owned by late best-selling writer and director, Michael Crichton. “This is one of the more remarkable collections of its kind in this country,” Christopher Burge, Christie’s International honorary chairman said as the works