Almost e-cigar in my country is smuggled goods (through border between the two countries Vietnam and China). You can use it everywhere (smoking ban is not widely) but I don't know if there is a problems if you entry through customs port when check in or check out at airport. You should disassemble all part of your e-cigar to avoid trouble. If you don't want to do this, just throw all your old e-cigar, you can buy it easily. This is an address of my favorite dealer, I usually buy spare-part, e-juice, etc... in his store
I spent 30 US dollars for a standard Ego kit (2 clearomizers, 2 rechargeable battery at 1100 mah, a USB charger, a wall charger, a bottle at 20ml e-juice). It is not a bargain but I think the price is acceptable because e-cigar is still rare in my country.