Bangai'O Spirits for NDS recently reduced to £12.71 on Amazon. Was previously part of GAME's 2 for £25 range, but is no longer there. Nearest price is Play.com who have it for £14.99. Some places also no longer stock this game, AFAIK.
People who need to look its score up on Metacritic need not apply (~82%), as you clearly do not know anything about Treasure.