One of my reasons to stop smoking and start vaping was definitely to save money. Based on the price of Marlboro Reds here in Ireland €9.50 (about $13.00 a pack).
If i replace my battery once every 3-4 months at a cost of €22.00 and use 2 clearomizers per month €13.95 (for 2) and use 80ml of juice per month, it works out like this.
Smoking Cigarettes €294.50 a month.
Vaping (as above) €38.45 a month.
So to answer your question, yes, definitely a HUGE saving! :-)