PayPal button Customization:

PayPal button ! you can change the default one first login to your paypal account then click the “Merchant Services” Now  click “Buy Now” button.

Now click Customize text or appearance(optional) here and you will see a button named “Use your own button image”

Now upload your created/customized button (.png) to your domain image file and copy the url including http:// and paste the url in the box bellow “Use your own button image”. Now you change the other required informations and hit saved button and you will get the html code now you copy this code and paste it anywhere you want to put show your button.

How to Edit saved button?

•     Log in to your PayPal account.
•     Click Profile near the top of the page.
•     Under My Profile, click My selling tools.
•     Click Update beside PayPal buttons.
•     Select the button you want to edit, and then click Edit from the Action menu.
•     Make your changes to the button, and then click Recreate.
•     Click Select Code to select the button code.
•     Copy and paste the button code in to your own web page code.

Also you can use custom image by following the above tutorial how to use new customize button?