Simply Games are selling "Valkyrie Profile: Lenneth" for the PSP for £7.00 (inc Del.)
You can also get cashback through the usual sites (e.g. 4% Quidco, making it just £6.72)
Next best price seems to be £9.99 from Play.
This game has a Game Rankings score of 81%.
Players assume a pivotal role in determining the outcome of the largest battle in Norse Mythology. On the eve of Ragnarok, a battle between the warring factions of Aesir and Vanir, Lenneth is dispatched to the land of mortals in pursuit of worthy allies. Her mission is a crucial one that could possibly sway the tides of war in her faction's favor. Approaching brave souls at the time of their death, Lenneth must convince these combatants to join her in the ultimate battle against evil. With time working against her, Lenneth must seek out, train and command an army of fallen soldiers in preparation for the final battle against Surt, the leader of the Vanir, while the mystery of Lenneth's identity unfolds. Special enhancements take advantage of the PSP system's capabilities - true 16:9 support and new CG sequences give players a deeper understanding of the plot and complement the game's dramatic storyline.Classic RPG in the palm of the hand - experience the adventure in the living room, on the road or outdoors A heart-wrenching tale of honour, courage and purpose in the afterlife - follow the fallen heroes as they pursue honor in the next life Time-based story progression breeds a non-linear experience where actions determine the outcome of Ragnarok - recruit well and Valhalla is saved, recruit poorly and destruction looms Encounter 24 unique characters with deep levels of customization Multiple endings that are revealed based on crucial world-altering decisions