fixed price for an option if it is 1 or 100 for example

[zws]

I need an option to choose yes or no for a print that have only once an extra price. If the client buy 1 or for example 100 of the product, this price is not changing with this option anyway. It is fixed if client choose it with print.
That is because it are basic cost for the print and it does not matter how much it has to be printed on the product.