Just buy cheap good stuff – mid-priced Smirnoff in blind taste tests with posh cocktail and spirit experts was the best-tasting vodka on the market. Maybe try this between you and your mates and then decide.
Water Filter / charcoal filter your Vodka or use Charcoal. Charcoal is awesome at filtering out microscopic impurities that affect taste and purity.
Buy a bottle of Grenadine – it makes even the poorest of cocktails look decent or make your own to save a few quid
Adding a good squeeze of lime, lemon, grapefruit etc juice will make even the poorest of drinks taste nice
Buy a bottle of Unique flavour enhancer AKA Angostura Bitters (44.7% alcohol) – found in tons of whiskey & gin cocktails
Learn how to make simple cocktails – cheap rum, mix it up with apple juice and pineapple juice – cheap gin, lemons, limes, oranges, etc, and add Sprite or Lemonade or tonic etc – cider + whiskey = ciderball – 1/8 lime juice + 2/8 grapefruit juice + 2/8 cheap tequila + 3/8 soda water/lemonade – cheap tequila + orange juice, then add a splash of grenadine AKA cheap mans Tequila Sunrise! – Cheeky Vimto = WKD (or unbranded equivalent + shot of port – 50ml cheap white rum, 25ml coconut cream, 25ml single cream and 200ml pineapple juice. – Long island ice tea – 25ml light rum, 25ml vodka, 25ml gin, 25ml tequila, 50ml lime juice, coke. p.s. sites like http://www.drinksmixer.com & UK Complex are good for hunting out other ideas