I currently use Paypal as my payment processor, but you don't need to have, or even need to create, an account to checkout.

You can checkout 100% as a guest, without registering or enrolling in anything.

You simply select "Don't have a Paypal account?" during the checkout process and enter your credit information as normal.

Don't want to use Paypal? I can also bill you via Square or you can send cash, check, money order or credit details through the mail.

see example