Hmmm... Well, I was taking 12 dropperfuls per day for the first week and I went through a 2oz bottle fairly quickly... Maybe in a little over a week. Now I'm taking 5 droppersfull per day and that seems like a good dose for me.
I'm not sure how the cost compares or if you are getting the one that I suggested also because it's not made with grain alcohol, but Unyquity makes some too (with grain alcohol) that might be less expensive (I'm not sure but worth checking.). Hers is high quality.
Make sure to let us know how it work for you! Also, keep in mind that for some it takes a little while before you notice anything. Also, Uny suggests between 6-18 droppersfull per day, so don't be afraid to take quite a bit. I would just experiment with it.