Yes it will be cheaper. How much depends on how much you were spending on tobacco and how much you vape. But you will save.
And, later down the road if you want to get into the rebuildable atomizers and mixing your own juice, you'll save ALOT more.
I know for my old Inferno, the heating elemnts cost about $12 or so for 3 of them. They burn out in approx 2 weeks. Not really bad though.
But with a rebuildables $20 worth of supplies will last a year or more.
Same with Juices. Once you have the stuff you need, it'll cost something like $1 or so per 15-30 bottle. But it takes a lot of practice, trial and error. You'll end up mixing some really horrid tasting stuff and some really amazing stuff as well.
Try to resist those craving if you get them. It'll pass in a few days.
I know with me, I had a few more so due to the fact of habit. I would always take my dog out and have a smoke. So it felt weird not taking her out as often and walking around to have a smoke.
So I think it was more of a habit thing for me to break, not really nicotine.