NaturesPremiere.com - Great customer service and free shipping (thru May I believe)
Amazon.com - Good prices and free quick shipping if you become a Prime Member. For us it was worth the extra few dollars. But now I believe there is a Mom's club that you can join and get Prime membership for free.
Zulilly.com - A MUST to join!!!!! It is free and just have to deal with one e-mail sent to you daily on exclusive sales. It is mostly designer clothing however, I have gotten a few cloth diapers and a FuzziBunz wet bag 1/2 price.
MrRebates.com - is good to join for money back on what you buy. Just go to their website and then shop where you want and you will get rebates to spend later. They will also let you know who is having any specials.