My answer: Lots.
The truth: It depends.
Real Simple has developed a wonderful online wine and liquor calculator for your wedding to help you figure out how much alcohol you should buy for your wedding. By selecting choices that pertain to your wedding such as full bar or wine, beer and champagne only, the calculator will help you determine how many bottles you should purchase. These numbers will vary depending on your number of guests as well as the time of day of your reception.