The Hello isn't *that* much bigger than an eGo, actually. And madvapes also has them...I think they sell a hello/cartomizer kit for $32.99.
The eGo cartomizers do come blank as well as prefilled. You have to fill them with a needle...just so you know. It's weird, but worth it. 2ml in one cartomizer...lasts a very long time. All vaping, no fussing.
The eGo batteries I have charge in 30 minutes or less...awesome!!! 
The eGo cartomizers do come blank as well as prefilled. You have to fill them with a needle...just so you know. It's weird, but worth it. 2ml in one cartomizer...lasts a very long time. All vaping, no fussing.