I need Facebook clone, I would like to start own website like Facebook ?

Sorry... if you need to ask this question... you have a LOT to learn before you will be ready to do it.

You should not buy Facebook clone scripts, they are full of bugs, it is much better choice to use established social networking software even if you don't get 100% of the look and feel of Facebook. Anyway my suggestion is to use elgg.org, it is free and open source rapid development framework. Other option is to buy commercial script, phpfox.com has UI most similar to Facebook.
I think you should first try elgg before giving any money for commercial script, you can find some info on cloning Facebook with elgg here - http://www.socialnetworq.com/facebook-clone