Zero Price + Ad to cart

Hi, I am trying to make a product for a print shop that is a free sample. This product has a opcion that, if the client need the design, they have to pay an extra $ 10.
The problem I have, and I don’t know how to solve it, is that: when I enable the calculation of prices based on personalized options and the client does not need design, therefore the product remains at a price of $ 0, the button to add to the shopping cart is disabled.
However, if I don’t enable the price calculation based on custom options and the price is $ 0, I can add to the cart.
In short, I need the product to be able to be added to the cart whether the price is $ 0 or the cost of $ 10 is added.
Is it possible to solve this?

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