Re wine. In 2007 we had, unopened, 2 bottles of liquor and 5 bottles of wine. The customs officer said that we owed duty on 3 bottles. She said duty on the wine was less than on liquor so she assessed the duty on the 3 extra bottles of wine. Cost $10.82. I would find it hard to believe duty would be any less than that today.
We are always over the allotted amount. We fulltime - we don't stock up, we just keep an assortment like you do at home. With over 20 crossings, this was the only time we have paid duty on excess. At the border I provide them with an itemized list, which includes an estimate of open bottles, plus full bottles. However, we very seldom have any full bottles of liquor, just wine.
We do a lot of wineries.