product option costs once

Hello,
I want to add some options to a product. It works fine.

But how can I add an option with a fix price independent of the quantity for this product?

For example:

I want to buy 100 pieces of the product. As option it must there be 50€ for a simple pressure plate or 75€ for an extended pressure plate.

The price for the pressure plate is independent of the product quantity.

Thx for help.

Thomas

Hi, did you manage to solve?