definitely give them money....its the most common wedding gift & generally the most appreciated....

a sari is not something you would use after you came back home....also, they are extremely difficult to wear....an alternate would be to pick up a couple of indo/western outfits from one of the local designers in delhi or mumbai....that is something you can always use later as well....if you want i could give you a few names of designers where you could buy stuff off the rack or get something made in a day or so....