If you have not yet purchased Starcraft 2, or have been waiting, there are multiple venues to Purchase through. I will provide some links through Amazon at the end of this post.
Basically, there are two different versions. a "Collector's edition" and a "normal edition" The CE is extra, however, it comes with the original Starcraft and Starcraft: Brood War on a flash drive, as well as a comic book, a book of concept art, as well as dvds which go behind the scenes, and detail certain parts of Starcraft 2 in the making. The CE also includes certain in-game perks which are otherwise unavailable, such as the Night Elf Banshee, Tauren Marine, as well as a few other exclusive portraits. It also includes an achievement which is otherwise unlockable.
If you do not want to splurge for the collectors edition, the the regular edition includes all necessary aspects to play the game. You just don't get those few covetous perks I mentioned earlier. Either way, you get a phenomenal and truly rewarding gaming experience out of Starcraft 2. Many people see it as just a game, but it is also a tool to help you refine your multitasking, and strategic analysis, which is an integral part in just about every career you will be pursuing. It helps to instill certain ideals such as "If you are high on monetary reserves, you are in trouble." Basically, this means, in a business context, if you have a lot of money that you have not invested into lucrative operations, then it is basically useless in comparison with other companies in your niche or field. That being said, money spent on non-lucrative, or wasteful spending, ends up hurting you in the long run as well.
Knowing and understanding concepts like these are integral in most careers, and playing Starcraft with a higher level of understanding will help you to achieve just that.