I've posted this about 20 times in the past, but here we go again:

I have brought back from europe 12-18 bottles of wine on many occasions. I have never paid duty. duty on 12 bottles is $3-4. I have even paid $500 duty on merchandise I was carrying in, and the wine was duty free.

There are state (maybe local) laws governing wine movement. In theory, customs officials enforce those laws. No such law in MD(bwi) or VA(iad). Do not know about the rest of the USA.

Packing.
1.The standard(professional) way wineries and the online retailers ship fine wines is to use a 225 lb(rating) cardboard box with styrafoam seperators. Made mainly in 12 packs, but also 6 packs. I have only moved 12 packs. I put it in a maxi (64") roller and check it. The wine usually weighs out at about 47 or 48lbs. The luggage adds 10 lbs, and puts one over the 50lb limit. Unzip the bag, show the GA the empty bag plus box, and they will usually check the pair.

If you are in the DC area, I can give you a box or two to carry over.

2. Do it yourself method. Get a good hardsided suitcase(antique sampsonite). Line the entire outside, and the center with big bubble bubblewrap. Put paper mache burgundy wine bottle separators down the middle of each side. This will hold up to 18 bottles. at 18btls, weighs about 75lbs. make certain the handle on the bag will support 75 lbs.

Carry on. Make certain you can add 25lbs to your carryon if you carry 6 bottles.

Champagne is heavier with all that glass.

Unless you are going to wineries in Italy or france, the prices in usa are very close to shelf prices in europe.