Product configuration in HostBill is made trough extremely flexible Forms, where you can choose whether certain form element should be free or paid option. Currently you can add pricing to Slider, QTY Input, Dropdown, Checkbox and Radio Select form elements.
Note: If you're configuring OnApp product you can fetch all Os templates into Form element to skip steps 1-3 - watch how.




Video: Result of configuring free / paid Form elements in order page.