Well, we just spent the week at Bible Camp with our denomination.  The opinion of alcohol consumption is mixed.  I believe most are against it, (we serve grape juice at communion), but there are a few in our congregation that do consume wine.  Our speaker was of German descent and he is in the process of changing to our denomination, most in our denomination are Norwegian, so his view was different than most of us in the audience.  He did partake in beer and wine consumption, which made a few of us squirm in our seats a bit.

The question about wine being so prevelant in Jesus time is legitimate.  The answer is that wine is the perserved form of grape juice, food preservation was different back then, I highly doubt that fresh grape juice was readily available at all times.  And in the example of the first miracle, Jesus was attending a Jewish wedding, a celebration. And, alcohol was used medicinally back then.  

Basically this is a grey area in most denominations.  For us personally we don't drink any kinds or forms of alcohol, or smoke as we find that those things would be offensive to Jesus and serve as stumbling blocks in our walk.

In response to the concern of the orginal question.  No, you should not feel obligated to sell those items to folks who do not posses the proper identification.  You are not Amish, I am guessing that you are a law abiding American and what if, an agent of the state of NY was undercover, dressing as an Amish person just to catch someone like yourself in the act of breaking a law.  If I were in your postion I would politely decline the sale, and if the person continued to persue the sale I would call the local authorities.