is subscribing to Amazon prime family for diapers/wipes the most cost effective?

J.
I know that extreme couponing would ultimately be the most cost effective of course but here in Hawaii that is difficult, so wondering any of you who subscribe to Amazon for diapers/wipes do you find your savings to be significant over store bought and if I may as could you share what you order, the frequency of delivery and your savings? I am already a Amazon prime subscriber. 
Or if anyone has other ideas of what's cheaper as far as buying diapers/wipes please share :) thanks!