THERE was strong competition among private buyers for the most expensive lots at Adams of Blackrock's sale last Tuesday, which resulted in some buoyant prices. A Vernis Martin display cabinet made Pounds 6,600, against a top estimate of Pounds 5,000; a good Victorian mahogany D-end extending dining table fetched Pounds 6,400; a set of 10 Victorian mahogany, balloon- back dining chairs sold for Pounds 3,400; a Victorian three-door bookcase made Pounds 2,900; a pair of mahogany single-door wardrobes, stamped Strahan, sold well above the estimate at Pounds 2,400; a set of six Victorian Cork rail-back chairs also sailed past their top estimate to make Pounds 2,200; and an early 19th century mahogany partner's desk fetched Pounds 2,300.