I'm also a traveler and always buy my cigarettes duty free. When I return to the States I always carry as many cartons as I can carry. The first two cartons I always get free. Depending on the which Home Land Security guard I get, they'll not fuss with 4 cartons but, if you go over their personal limit, you will pay for ALL cartons above 2. The fee is a flat $2.50 /ctn which could be a 100% penalty depending on which country you're coming from, that's highway robbery except without the road! Once home I have go to a place like TobaccoTrain.com to continue to receive cartons duty free. CAUTION: When flying in, always fill out the Customs Form COMPLETELY to avoid confiscation or fines.

