"FreshBooks" Mapping fields and pulling cost from check box selection.

Figured out how to create a client based on the name email ect.. that someone fills out on a form.. Just having trouble figuring out how to pull cost on these check box selection on my page.. http://webdesign.scottheliker.com/packages/get-estimate/

Here is a screen shot explaining what I am trying to do.. Is this the right way that I am going about it?? These are add ons for website development and I want the data passed to freshbook based on the addons that one selects so it will populate everything in Fresh Books allowing me to only having to send the invoice
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Screen cap
http://i131.photobucket.com/albums/p291/scott7414/gravityforms.png

Thanks Scott