Is buying mobiles from internet sites safe?

I want blackberry storm9530 but it is available only on internet. should i go for it or not. they are selling it at big discounts whereas the set is already stopped by BB way before. how r they selling then and why do they give only 6 months seller warranty instead of 1 yr manufacturer warranty ?are those sets original and new or not ? hey frnds please help if u hv ny idea...plzzzzzz