Integrate Constant Contact API

I have a team of coders working on our website, but they don't have experience w/ constant contact so I want to outsource this part of the code. We're looking to do something basic like this - [login to view URL] I would like the form to do all the checking and handling without leaving the page. If a contact is already on the list, or any other type of message, this should all take place within the page itself. Please provide me a quote to setup this api functionality. Thank you!