Contest prizes based on Facebook Likes or ReTweets may not be fair because one can buy the FB likes and Tweets.
Just search "Buy Facebook Like" in Google and see the result. In previous contest the third prize was Rs 10,000/- fuel voucher and now in the new contest it's Rs 50,000/- gift voucher. To bag these attractive gifts people may buy the FB likes from professional bookmarkers. 1000 Facebook like costs less than Rs 5000/- only(Just quoted from one of such sites).
Indi admins, reconcile the rules, better late than never.