The spring print auctions ended last week and prices continued to tumble. Unlike the fat catalogues of last fall, the offerings at both Christie’s and Sotheby’s were smaller -- Christie’s 228-lot sale on Apr. 28 was its smallest since the art-market crash of 1989. Sotheby’s two-day auction on Apr. 30 and May 1 featured 346 lots, substantially fewer than the 570 works offered in the six months ago.