I am trying to scope out the development effort associated with implementing the "login with Facebook" option on our website. We operate a fairly large eCommerce travel website running on a JSP environment. We have already a user account feature, based on a MySQL database. The only requirement for a user to create an account currently is to provide an email address as their loginId and a password.
In order to make it even easier for users to register and sign-in to our site, we would like to offer a "login with facebook" button (just like Kayak.com does), so that a user can register to our site based on their Facebook account. By authorizing our application, we would pull their email information and create an account on our website.
My assumption is that this would be a relatively simple maintenance project, costing 10 Man Days of development & QA max. I would like to get some feedback from other webmasters that have implemented a similar feature to see if my rough estimate is in line with reality. Thanks in advance for the insights you can share with me.