(Disclosure: This site contains product affiliate links. We may receive a commission if you make a purchase after clicking on one of these links. Read our affiliate disclosure for more info.)
Saints Row: The Third is on sale for $15.29 (66% off) at GameFly as one of their Store Specials. The game uses Steamworks so Steam is required.
This is just the base game so if you want all the DLCs at the same time, you might want to wait for a GOTY edition or something.