You would think that after the dismal performances of the contemporary art sales at Christie's and Sotheby's earlier this week, sellers might recognize the need to reduce reserve prices if they were to have any hope of selling anything. At Phillips de Pury & Co.'s auction last night, estimates set before the markers unraveled remained in place, despite the fact that the auction house had tried to persuade people that the figures were now too optimistic. Sellers "had a luxury of eight years of the climbing prices,'' said Phillips senior partner Michael McGinnis. "They were not receptive.''