I believe I understand what you are trying to do. I assume that you have a number of items to ensure, like Passport, Medical expenses, and so on. Next to each on on the user interface, you want three checkboxes, one for each of the three coverage levels normal, premium, and luxury. When a user selects one of these options, the total price is calculated using the selection. The fastest way to accomplish this is to use the 'radio button' widget that is included in Mendix by default. This will ensure that if a user selects 'basic' and then selects 'premium' then basic will be automatically un-selected. I recommend the following:
1) Create a new enumeration with three possible values: basic, premium, and luxury
2) For each product (passport, medical, etc) create an attribute called 'coverage level' that is an enumeration value. Reference the enumeration from step 1
3) on your page, have a list view for each of the products and in that list view, put the 'product name' and 'coverage level' on the page. In the later versions of Mendix, putting an enumeration value on the page automatically adds a radio button widget.
4) on the radio button widget, set up an 'on change' microflow that will re-calculate the value of the insurance using the selected enumeration value.
For more information about enumerations, check this out
Hope this helps,