The Underground DLC for Vita is £1.59 at PS Store for 2 weeks, however at the moment of posting this it is possible to download it for free.
When you open it from the vita - there are two links
1) Buy it at £1.59
2) Download Free - A presto!
The pack includes 21 new challenges, four fresh outfits and a handful of extra Trophies to unlock. It’ll set you back just $1.99 during its first two weeks on sale, before returning to its normal price point of $4.99 on 14th August.
Also due out later today is a brand new patch for the monochrome masterpiece. In addition to minor bug fixes, the update assigns the squeeze mechanic to the Circle button – allowing you to relieve Lil of his rather severe case of irritable bowel syndrome with new-found ease.