All of the other Seasons are on sale too at $15.99. I'd do a direct link to the video store, but it won't load on my phone. Make sure you click on Buy Season and not the individual episodes. There's an "ad" for this on the dashboard for me, but it takes me to the list of episodes when I click it. You need to Go to Series in order to purchase the whole thing. Season 1 will only show up as free this way.

Also keep in mind this is the only season they have in HD. If you are looking to take advantage of the sale (it ends up being about $5-$15 cheaper per season than buying the DVDs), everything else is in 480p. I already have the DVD sets of the show, but getting the first 39 episodes of the series for free is too good to pass up.