Here are some great tips for keeping your bar tab affordable on your big day from Bartender Mayur Subbarao via Martha Stewart Weddings.
Q: What's the cheapest way to have an open bar?
A: The secret is to avoid premium spirits (save the Johnny Walker Blue for the honeymoon), and pare down your selection. If you stick to the basics and offer just one or two midrange bottles of each type of liquor, you'll come in around $20 a head. Stock a red and a white wine and a couple of beers, plus Scotch, bourbon, gin, rum, and vodka. Then gather an array of mixers like sodas and tonic; bottled orange, grapefruit, and cranberry juices; and fresh-squeezed lemon and lime juices.
Q: And what about specialty drinks?
A: I love them. To save time and money, make batches in advance. If the recipe calls for one or two liquors...leave them out until serving time. Then return unopened bottles.