How can I replace the free word on products with no price?

I have a form where one of the options is at no charge but alternatives have a price. I would like it to say "No Charge" or something similar but it says "FREE". Is there any way to change this? It would REALLY help us out!

Thanks!
Travis

It is possible to achieve it with some CSS code, injecting this one should replace the "Free" word by the "No charge":

span#input_13_1019_price {

    font-size: 0px;

}

span#input_13_1019_price:after {

    content: "No charge";

    font-size: 15px;

}

This guide will help you injecting the code: https://www.jotform.com/help/117-How-to-Inject-Custom-CSS-Codes 

If you would add a new free product and want to replace the "Free" word then you would only need to right click on the price or free word and copy the <span> element ID:

Replace the copied ID on the code given above (green highlighted text).

Hope this helps.