Determine Cost Based On Location

Site/page url: https://www.theenrichededucator.com/workshops/in-person-on-site-training

Hello,

I offer add-on services to my products (services). One add-on service I provide is "in-person/on-site training". I travel for my consulting services, so I would like to be able to automatically determine the additional cost for potential clients I'd serve outside of the Atlanta, GA area. Ideally, a visitor would be able to enter their zip code and an updated calculated cost of the add-on service would appear and they can add it to their cart (named "registration" on my site). 

I've looked around for possible solutions and I think I might need to go with some type of API (such as this one). I imagine this would work something like this:

1. Visitor enters zip code
   • The API would calculate the distance between my zip code and theirs, then pass the distance back to my site.
   • Use the distance to calculate the cost based on my table (pictured in screenshot below)
2. Distance displays on the page
3. The new cost updates and displays on the page
4. Client adds service (with the updated/correct cost) to cart/registration 

I'm not sure where to start or how to get this going and would appreciate any help.