Hello Shatrughan,
This is fairly easy to do.
Every time someone visits a page and hits the Buy Now button, you can raise an event called 'Buy Now' (It can be named anything you'd like).
This event can have a property called 'URL' or "Page Title" which passes on the page title when a user clicks on 'Buy Now'.
Something like
Buy Now
{
PageTitle=Home
}
This will later allow you to segment all people who clicked Buy Now by URL/PageTitle they visited.
Hope this helps