Shameless plug here, but if your diet or inclination points you toward specialty foods (organics, gluten free, and so forth) or vitamins and the like, then the site Vitacost is making a serious effort to move into this space.
If you're interested, they have a referral program -- follow this link, sign up for an account, and spend $30 or more, then you and I each get a $10 credit.
https://www.vitacostrewards.com/dytgZnj
In my experience, they generally have prices that are pretty competitive with local retailers or online competitors, and then they run a variety of specials that sometimes give them an actual edge. In any event, I have ordered twice, and have been pretty pleased. They also do a subsrcibe-and-save option, which is a no-risk additional savings.