Every once in awhile we are asked whether a cash bar is appropriate for a wedding, and my answer is always "Sorry, but no." Some brides still choose (for budget reasons) to pay for a few hours of hosted bar package, then change the last hour of the reception to a cash bar for those who are still drinking. Here is my advice: Cut back where you need to in order to cover the bar tab. You are hosting this event and inviting guests to a beautiful ceremony and party. Please don't invite them then hand them a bill.
Southern Weddings Blog just did a great post on this very topic, in which they quoted the ultimate in etiquette, Emily Post. She says:
"Just imagine being invited to a dinner party at which the host or hostess handed guests a bill. You'd be shocked. A wedding is no different; the couple and their families are hosts, not restaurateurs. You might cut costs by serving simple hors d'oeuvres, wedding cake, and nonalcoholic punch at an afternoon reception; planning a home reception to eliminate the expense of a rented hall or hotel; or limiting the number of guests you invite. You don't have to have a bar; if you want champagne, you could limit it to one or two glasses per guest for toasting. There are many ways to stage a beautiful wedding on a tight budget, but charging guests isn't one of them."
Other ways to be creative include offering beer and wine only, holding the wedding at a venue that will allow you to bring in your own alcohol, or offering guests one or two types of signature cocktails rather than a full open bar.