Changing a bike that has flat bars to one with drops involves ponying up a lot of dough for the swap. Not only do you need new bars, but depending on the width, you'll also need a new stem. Other than that, you'll need new shifters/brakes. The nicest but most expensive version of these is the brifter (integrated shifter/brake) but they cost a couple of hundred for a low end version.

Besides the expense you're adding drops to a geometry that wasn't necessarily designed for them and this could cause discomfort....not necessarily, but it is a possibility.

You're better off saving a little longer and getting a bike with drops if that's what you think you want. Take a couple for test rides before making up your mind.