First all of Telltale's [iPad damn it] games are now $2.99 until February 10th. Of course, no new episodes have been released yet, and chances are slim they will be if history is anything to go buy. (The Penal Zone has been out for closing in on a year now.)
Also, if you haven't subscribed to their newsletter, you probably should, as the newest edition has some new Back to the Future images. Which is awesome. They're also offering the full season of Sam & Max: Beyond Time and Space for $4.99 to newsletter subscribers.
So yes. Do it. And stuff.