Whether you're entertaining for a large gathering or just looking for the most cost-effective way to fully stock your home bar, buying liquor in bulk is the best way to go. Here are some ideas on where to shop.
Call your local liquor sellers and see if you can get a bulk deal from them. Many of them may be willing to do this if you pay part or all of the price up front and give them ample time to arrange for what you need.
Check local warehouse clubs. Stores such as Sam's Club and Costco can offer excellent savings on large amounts of alcoholic beverages, and depending on the laws of the state you live in, many of these types of stores are required to sell liquor to anyone, including those who don't already have a membership.
If there is a brewery or distillery in your area, call to see what your options are for buying directly from them. Many beer breweries will sell growlers (large bottles of discount beer) or kegs directly to the public.
Order online. There are a number of bulk wine sellers and some full-service liquor sellers online (see Resources below).