Valkyria Chronicles 2 launched a substantial DLC pack yesterday which will net you 22 new missions for the price of $4.99 on PSN. This pack contrasts with how the DLC was released in Japan where you could purchase each mission separately for about $1. Not bad in way of savings.
In addition, SEGA also released another four free codes that you can enter to receive tank stickers, free missions, and even unlockable characters. You can redeem these codes in the Extras section from the title screen (under Password):