In my first few months of vaping, I spent a bit more, as I ended up with a LOT of juices that I couldn't vape. I was very curious about all of the available flavors, and it was a lot of fun getting new samplers in the mail for a while. Fortunately, I learned that I could trade or sell them here, and I managed to trade anything I couldn't vape for something that I could. Now, I stick with 2-3 flavors that I know are dependable, and only order a small sample of something new very rarely.
My other big money waster was getting a bottom feeder mod, which worked out terribly for me. It was a very well-loved model that is very popular here, but I had a bad time with it., Had to send it in for repair three times, and it burned through attomizers at the rate of one every other day, so I was spending close to what I used to on cigarettes.
Fortunately, I sold my mod, now I am very happy with my eGo with LR atties that last me at leats a couple of weeks each. So, now I probably spend about $80/month on average - about $55 of that goes to juice, $12 for atties, and throw in a few extra bucks towards the occasional new battery and spare charger that I buy. That's a little bit less than what I used to spend on a carton of cigarettes each week, so I would say I'm definitely ahead of the game.
In the beginning, I think it's perfectly justified to overspend a little. After all, you're replacing a deadly addiction with a new hobby, so you might as well enjoy it and try out as many things that interest you until you settle into it.