I don't think India is too concerned about your having an onward/return ticket - though of course you will require a visa. But one country which may be on your itinerary and does have this requirement is Thailand. Also, if during your trip you decide to fly from one country to another, rather than go overland or by sea, the airline company may not fly you if they think you may not be granted entry. Some years ago, we flew from Hong Kong to Thailand, to travel overland down to Bali, from where we flew home via Singapore; and the Qantas checkin at HK insisted on seeing the homeward ticket, to ensure the Thai authorities would let us in - even though we had specially obtained a Thai visa to ensure entry. So, all in all, perhaps you should buy a return ticket from the final desitination on your itinerary. (It is also worth bearing in mind that any country may refuse you entry if they consider that you may become stranded on their territory without a ticket or adequate funds.)