remery said..
I wouldn't over think things, get out there with whatever you can get your hands on. The bug will attach itself and you will upgrading soon.
Agreed. Making sure you are on the right type/size of board for you skill level and conditions is the most important. Right sail size for the wind your in is next most important. The board size changes quite dramatically as you get better, so don't invest too much time and effort in fixing something that you may not end up using long term.
Booms and masts of the kind of things that you don't change as often as sails, so you can make a case for spending more on those things even at this stage as they last a long time generally. However it's going to make a marginal physical difference at your stage so I would just hit the water with what you have. And buy replacement when stuff breaks or it isn't the correct size.
You will spend more money on gear, I just don't think you know now exactly what you need the most, as mentioned above it may be a bigger sail