How much research have you done thus far on reception venues and have you discovered that many reception venues allow and even encourage their parties to bring in their own alcohol?
By bringing your own alcohol to your wedding reception venue you will literally save thousands of dollars. The venue will still more than likely provide bartenders or staff people who will serve the drinks to people and will provide you with coffee, water and soft drinks.
If you proceed with this route and intend to provide your own alcohol at your reception venue you should base the amount of alcohol you purchase off the theory of 3 drinks per person. This weighs in the fact that some people will not drink at all and some people will have many more than three drinks.
Take the alcohol to the reception venue a few days before your scheduled reception. This will allow the staff to familiarize themselves with the liquor and wine choices as well as get it off your plate and make that one less thing you would need to do the day of or the day before your wedding and reception.