I would like to know if it is possible to define an option variant such that its price modifier adds that cost to the final price in the cart, not to the item price?
For example, my vendor sells cupcakes for $4.00 each. I want to create a product option to "Add a greeting message: +$2".
The current behavior is that cupcake price is increased to $6.00/each. This is not desirable, since buyer can buy a dozen cupcakes, I want only the final cart price to be increased by $2 due to this option.
The "Add a greeting message" is a one time cost irrespective of number of cupcakes purchased.
Our EZ Checkout Summary Fields addon was written for this exact purpose. You can have fields of many different types and you can also have the fields be specific to a product. I.e. only add when product XYZ is in the cart.
Note that this is done at checkout, not on the cart page.