I think MATLAB is easier than dealing with Excel's VBA. And obviously, much easier than dealing with C++ or Java (but less powerful). If you don't want to spend the money on MATLAB yet, start with Octave. Anything you learn and write with that can be transferred if you then switch to MATLAB (which you would do if you are interested in making GUIs, elaborate graphs, or other more advanced stuff). In my opinion, forget buying any books. Find a couple online tutorials, pick up the basics, try your own program and google search to learn any functions you need for it. Also check out the MATLAB user community on their website to learn from others. A good rule to try to keep your programming efficient for MATLAB is, always try to think of a way to do what you want without writing 'for' or 'while' loops, often it is possible.
I'm surprised that no one has mentioned SCILAB, the open source equivalent to MATLAB. It can even run .M files.
I think posters mentioned Octave and not SciLab because Octave is much closer in syntax to Matlab. Read more here.