I accept payments via pages at PayPal.com. PayPal is a secure system used by many merchants. You do not need to have or create a PayPal account. You can use any major credit card for the transaction without logging into an account.
My account at PayPal is for my crossword game, so it will show the company name as WildWords Game Company. Unfortunately, I have few games left. That site is wildwords.us should you wish to verify the association.
Set the amount as you wish from $5 up in the "Price Per Item" box that will appear. Extras appreciated, but any payment at all is optional.