[Plugin: Gravity Forms] Conditional purchases with Paypal?

Hello, I’m trying to figure out if it is possible to create a form that allows someone to select a number of people (1-4), then gather information about each person, then allow them to pay a specific amount based on how many people were selected (using Paypal).

I am currently using Gravity forms and I have figured out how to use the Conditional Logic feature to allow the various chunks of info to show up per person after they select how many. The part i’m mostly unsure of is how I can base the Paypal charge on how many people are selected? I have not purchased the Paypal plugin for it yet because I wanted to make sure this would work before I did, so if this is a simple part of the plugin please let me know. Or if you know of a better option/plugin to use please let me know.

Here is a site that is doing what im basically looking for: http://www.2livebeyond.com/register/