Form that creates notification If user is in a certain city
I run a headlight restoration business in the Dallas area. On my contact form, I have the person put in which city they're in. I want to charge an additional travel fee if the person is outside a certain area or distance from me.
I would like to have a message/popup come up when they submit the form that tells them there may be extra cost involved, based on the city they fill in. Yes, I understand I can also have that message on the form page itself, but I want to make sure they really see it.
Can any of you point me in the right direction on how that could be accomplished? Thanks in advance.