buy the used studio and enjoy it throughout your high school years... once high school graduation rolls around put together all the money folks send you, the money you can get from selling the studio, and any money youve saved up from now till then and get a put that towards a custom =) as far as differences there are a handfull to consider but to sum it up in a simple way i like to use analogys...
think of the studio as a this,
think of the custom as this...
they are both nice, ones just nicer lol...