Drop Down List Options

I'm a newbie, so maybe I'm not understanding drop down lists. Here is what I'm trying to accomplish.

I have form that there will be three choices. Each choice should generate a set amount. It should be as follows:

Choice 1:  Box is not checked. If this choice is selected, then I want the form to generate - 0.00

Choice 2:  Married. If this choice is selected, then I want the form to generate - 12,900.00

Choice 3:  Single. If this choice is selected, then I want the form to generate - 8,600.00

Is this possible? In the Dropdown Properties - Options - Item - I entered "Box Not Checked", then in Export Value - I entered - "0.00". And then did the same for the other items I wanted in the list. But when I did it this way, and tried to use the form, it simply showed the "Item" on the form.

I'm afraid I'll need to write some type of script from the googling, I've been doing. And if that's the case, where do I go to learn how to write scripts?

Thank you to anyone that can help.