zero-gravity, it all boils down to three aspects-
1. What genre of music you will endeavor to create.
2. Your knowledge of music theory.
3. How focused/committed you wish to be on music composition.
If you want to compose Ambiance, per instance, there are programs that have a better setup for that (or so I am told). If you know nothing of music, shy away from programs that rely heavily on musical notation and lean more on either piano-scroll or related notation/entry methods. If you plan to do it as an occasional hobby with no real focus, consider a free program until you get going.
Money also matters. You can't buy very good stuff with $180, but you can get a start on what you need.
If you don't know much about music but want to write it, I heavily caution you to enroll in a music theory class or two, or even browse this forum or elsewhere for tutorials (I know of a few good basic music theory guides out there... and there ARE tons of resources out there) before even putting down your pen, so to speak.