I was wondering if there was a way that we could set it up so that we could offer a one time discount to people who like a specific Facebook page.
Offering a discount for liking a Facebook Page
Not directly with s2Member, no. There might be some way to use a link to a specific page that is displayed only to those who like you page on Facebook, but that really has nothing to do with s2Member. I’d suggest asking on forums about Facebook marketing or something like that.