I initially purchased a few 510 with PCC kits. In total my initial purchase included:
3 PCC's
8 Batteries + atty's, juice, etc.
I have lost 1 battery because it must have fallen out of my pocket and 1 battery died. I still have unopened batteries for when the ones I'm using die. I also have 1 PCC that died, 1 still functioning, and 1 unopened.
The only thing I purchase on a regular basis is cartomizers (they work much better than attys on the 510) and juice. I spend about $20-$30 per month on juice and cartos.
I have been vaping for nearly 2 years and was spending over $300 per month back when I was smoking a pack a day.