With Buy Now Button Extension you can manage numbers of Custom “Buy Now Button” to maximize Store Sale. You can display Buy Now on any Product which makes customers to Checkout lot easier.
You have a lot of customization options also.
1- A Custom Title
2- Button Text
3- Select Font Family
4- Button Radius
5- Button Background
6- Button Color

Powerful Key Features
~ Add Custom ‘Buy Now’ buttons to Store
~ Manage Multiple ‘Buy Now’ buttons as CTA
~ Display ‘Buy Now’ option on selected Products
~ Restrict by Particular customer groups, Store Views
~ Try various personalization options

Complete Detail - https://marketplace.magento.com/fme-buy-now-button.html#bazaarvoice.reviews.tab