How can I track form submissions in Google Analytics and apply a monetary value

Hi Folks,

I'm wanting to launch some Ads for my business but before I do, I want to have my conversion tracking set up appropriately in GA. A conversion for me is someone getting in touch via one of our contact us forms on the site. I've worked out based on Avg Deal Val / Conversion % of prospects spoken to, what a monetary value for each form submission should be worth and would like to apply this to the tracking on the dashboard in GA. What is the best way to do this?

Thanks,