Need small help on a script

Hi All,

I need someone to help me by writing a script to purchase a product on a eCommerce site. This sale happens once in a week and goes off on a particular day and time( I will know the date in advance) and it goes out of stock in matters of seconds and sometimes in 1 second. The script should be very fast in clicking the buy now button which appears on the site.

http://ift.tt/1dvHQ0Z