I've only been vaping for a week, and I've spent about $180. However, I feel like given my current supplies, I could easily go another month or more without having to restock:
-Janty Ego set, w/ two batteries, 5 carts, one atty and a charger
-140 ml of various juices
-5 extra attys
I am very happy that I went with the Ego for one reason; battery life. From lots of reviews, and the trials of a good friend who got a 510, you spend just as much on a 510 setup that will last all day (extra batteries, PPC's, etc...) as an Ego set. The brilliance of the 510 from my estimations are the vapor quality, which relates to the atty, which the Ego utilizes as well. Not to down the 510, since it is the standard, but I couldn't be happier with the performance of the Ego. And no, I'm not a Janty spokesman
From appearances, people start throwing down the big bucks when they "want" more (i.e. different second or third units, mods, etc...) as opposed to "needing" more.
However, I'm only a week in, so I haven't experienced too much...