Buying cigarettes from overseas

Hi everyone.
Does anyone know if it is possible to purchase cigarettes from overseas.
When I was on a business trip in the USA in 2003, there was another guy there (not ozzy) who was buying cigarettes from Puerto-Rico or another country. He was not allowed to buy more than I reckon a couple of boxes at once, so he just bought them as he needed. Otherwise he would have to pay very high custom taxes.
My understanding that our situation is pretty similar, so we should be able to do the same thing.
Does anyone know good reliable overseas (online) stores where I could buy cigarettes for my father who is coming to see me and will stay with us for a few months. He is quite a heavy smoker and it would cost me a fortune to buy cigarettes for him.
It would be also good to know what's the limit. Is it similar to the USA - two packs ?
Thanks.