Welcome!
I've had Pro for almost a year now, and I haven't needed to buy any 3d world builders yet, because I'm learning 2d first, it's easier.
Listen to Daemon, there is so much experience required in making games that you pretty much have to invest several months working your way up to more complicated programs. I had programmed before, but when I got interested in making games I got DBP one of the first projects I started was my RPG, wow was that a mistake. Now, I have improved enough to actually make a game worth playing. In fact, I'm in the process of writing a tutorial, you'll see it in the forums soon.