Step 1. Make a Radio Button in Contact Form 7 but manually add the attribute: free_text as shown in the example below along with a name for your input box such as Other:
Step 2: On the PayPal tab place the items code in the Price Code field as shown below:
This is how the radio button will appear on your site:
When you go to PayPal the amount will be whatever was entered in the Radio button input box:
