Now comes brands . Typically, there are couple of brands very active in India such as Pampers, Mamy Poko Pants, Huggies , Wipro and Baby Hug.
The next thing is which all style. Actually there are two styles one is pant style another is non pant style. You can choose based on the need.
Now comes discounts... there are sites like Bundlebaazi that is giving discounts on buying on bulk, like when you buy online diapers, you can buy in 2 or more to realize the maximum benefit out of it.
Also, Check out couple of coupon sites as they keep on publishing coupons.