Gameplay are selling "Puzzle Quest: Challenge of the Warlords" for £19.99 (inc Del.).
You can also get cashback through the usual sites. (e.g. 11% from Quidco making it just £17.79)
Next best price seems to be £23.99 from PowerplayDirect.
Puzzle Quest: Challenge of the Warlords is a brand new, genre-bending title that ups the ante on traditional puzzle games by incorporating strategy, role-playing elements and a persistent storyline. Set in the Warlords universe, the game challenges players to save the land of Etheria from evil Lord Bane as gamers engage in battles fought by means of competitive, head-to-head 'match-three' style puzzle games in one of three gameplay modes: Single-player, Instant Action or Multiplayer. Victory will advance a player's customizable hero, magical arsenal, creature companions and more - ultimately rewarding gamers at nearly every turn and deepening their immersion into the richly diverse world. The game's remarkable mix of classic puzzle gameplay and an abundant suite of characters, customizations, spells, companions, tamable monsters and more provides a fresh take on the puzzle genre that offers endless hours of replayability. Designed specifically for handheld gaming systems, Puzzle Quest can be enjoyed in long or short doses, cultivating a casual but deeply satisfying and compelling gameplay experience.