Haven't tried it with a Paypal link but don't see why it won't work... See the scrapbook video http://www.concrete5.org/documentation/general-topics/scrapbooks/... to see about adding a block to a page type.
This should add it automatically every time you create a page.

Thank you! I set up the defaults for the template to include the add-on. Here's how I did it:

1) Go to Dashboard
2) Click on "Pages and Themes" in the left sidebar
3) Click top tab called "Page Types"
4) Click on "Defaults" of the template you want to modify across the website (you'll need to do this for all templates you want to add the add-on to
5) Edit template and place add-on in the template

Now, before getting out of Edit mode for that template, do the following:

6) Click on the area where you placed the add-on, and click on "Setup on Child Pages"
7) Select all pages that you want the add-on to show up on
8) Exit edit mode and save

Then, you're done. I hope this helps someone else.

...and add the scrapbook block to your Page Type Defaults.

Dashboard > Pages and Themes > Your Page Type > Defaults