Instacart prices are consistently more expensive than having it delivered from the stores directly (including a shipping fee). Here in NYC, where grocery prices are already expensive, it aches me to pay even more.

Seems like NYtimes (1) had done an article on Instacart being expensive (and Instacart's FAQ says that they add a markup)

Google Express is not a competition yet. They do not carry many popular products / perishables.

(1)- http://www.nytimes.com/2014/05/22/technology/personaltech/on...