You certainly can save a lot of money with vaping, if that is your goal. For most people here, the goal is to enjoy vaping as a sort of hobby by trying lots of devices and juices.
For me, vaping is a means to an end -- to quit nicotine altogether. I've been analog-free for 4 weeks, and have recorded every penny I've spent on vaping supplies, and compared that to $8.50 a day for cigs. So far, I'm in the hole by about $100 (spent $350 on vaping, used to spend $250/month on cigs).
BUT, all that early spending was a lot of trial and error. I wasted over $100 on a gas station model and replacement cartos, wasted over $50 on juice I can't stand (Johnson Creek, I'm looking in your direction), etc. I'm now happy with my setup (2 eGo batts, 2 Riva batts, 15 LR cartos, 50 ML RY4 juice). I have no desire to mess around with mods, try every juice out there, etc.
I'll need more juice in a few weeks and new cartos eventually, but I'm tracking all of this and my break-even date is 11/7/11. After that, $60 a month on juice and cartos means I'm saving almost $200 a month over smoking.