This site. This page has no sign-up forms, accounts or ad tracking.
Purchases. Purchases are handled entirely by Gumroad, which collects your name, email and payment details under its own privacy policy. I never see or store your card details.
Emails to me. If you email me at barncatbetty@icloud.com, I use your email address only to reply to you, and I never sell or share it. To have your emails deleted, just ask at the same address.