Client side javascript

I don't know how to do this but I thought one of you might know where to look.

I want a visitor to fill out a form that lets them choose between several options that would result in them paying a different price for a service. If this form was just getting submitted then I could just use radio buttons and everything would be fine. But, in this instance depending on which radio button they choose the price would be different. So, after they hit submit I want the total price to display for them based on the information they put into the form.

If you have any information, let me know.

Thanks,

Brooke