The FAQ is outdated. I'll see about getting it updated.

To donate and/or purchase a PBF:

1) Go to http://www.carrionfields.net/donate.php
2) Click on the yellow "Donate" PayPal button.
3) Continue through PayPal, making sure to add the character name in the notes to seller box if it's for a PBF.

I could've sworn at one point it allowed you to specify the amount, but that doesn't seem to work anymore so unfortunately if you want to purchase multiple characters you may need to donate multiple times unless I'm just missing something. I will look into that as well.