Shannon,
Some of the liquor stores close to where I live/work have empty cases sitting up front for people that purchase a mixed case of wine. I will buy a bottle of wine now and then and just ask if I can take a couple of cases and have yet to be turned down, especially if the stock is high.
In addition, Costco tends to have lots of boxes. While they may not have wine case boxes in their original form, they may have some other boxes that will work if you wrap the bottles in something that will preventglass-on-glass contact (those green plastic web things from the liquor store,strips of cardboard, paper towels, etc.).
Hopefully the liquor store or even a grocery store will have empty case wine boxes for you in lieu of some kind of shippers.
- Jim