Buying by the case helps, not initially cheap, the price per/oz is cheaper. It helps in the long run.
I buy a case of red label Smirnoff every 2 months or so for the wife and myself, 10% off by the case, its normally about $100 for six 1.75L bottles. Smirnoff is a good middle grade Vodka that wont make you feel like hell the next day, well for me anyway. Big glass of ice, can seltzer water, and 2-4oz of vodka is a nice daycap.