$19.99 for 5 DLC packs.
Warner Bros. has just announced the Season Pass for Batman: Arkham Origins, which will be available for £15.99/$19.99/€19.99. Purchasing the Pass will save you $10 in the long run.
The full list includes:
Goth by Gaslight and Brightest Day Batman skins, New Millennium Skins Pack, Infinite Earths Skins Pack, an Initiation bundle which will allow you to play as Bruce Wayne before he was Batman, and a new campaign.