The UK
Star Trek bargains for June are now live. 99p each as ever.
The three individual parts of Peter David's The Returned, which is the final published story to date in the New Frontier range.
Christopher L Bennett's two novels (Watching the Clock / Forgotten History) and three novellas (The Collectors / Time Lock / Shield of the Gods) from the Department of Temporal Investigations series, featuring Agents Lucsly and Dulmer as they deal with all the timey-wimey stuff the rest of Starfleet isn't allowed to dirty its hands with.
And then the ones that are probably of most interest to most people.
Star Trek II: The Wrath of Khan - Vonda N McIntyre
The Eugenics Wars: The Rise and Fall of Khan Noonien Singh: Volume One - Greg Cox
The Eugenics Wars: The Rise and Fall of Khan Noonien Singh: Volume Two - Greg Cox
To Reign in Hell: The Exile of Khan Noonien Singh - Greg Cox
The first should need no explanation, the middle two deal with Khan's life prior to the 1967 television episode Space Seed, and the last is set after Kirk strands the Botany Bay on Ceti Alpha V and prior to The Wrath of Khan.