(January 2023 edit: Amazon has announced they are phasing out their Amazon Smile program, so unfortunately this option is no longer available. However keep an eye out for similar programs from retailers and employers which allow a portion of your spending or pre-tax income to go to a nonprofit of your choice.)
If you have an Amazon account, go to smile.amazon.com, sign in, and choose a nonprofit organization you’d like to support. Amazon will donate a (small) portion of your purchases to that organization. You can search directly or contact your favorite pro-life orgs and ask them if they are eligible for Amazon Smile. There is no extra cost to you for this service.
How To Be Pro-Life 