as in topic. got this option. why shall I buy the beta kit?

At this point, the only reason to buy the Beta book is if you want to get a jump-start on playing Star Wars under this new system.

The final version of the EotE corebook is slated for a Spring 2013 release, so it's also a question of how long you're willing to wait.

If you're just interested in seeing what the basic rules are, there's the Beginner Box which includes a Rulebook that has all the fundamental rules that you'd find in the Beta book as well as including many of the updates that were made since the Beta book was published back in August.

thanks. will wait for beginner pack in Europe.