you can find cheaper wall cube chargers, but delta peak final charge detection is more efficient and takes care of the battery. a good option could be the Maxim 712/713 battery charger controller. i developed some years ago a charger for home use, selectable 4-5-6-7-8 cells NiCd- NiMh charger with charge current also selectable in 500 ma steps, with good succes. In the maxim datasheet, you can find all necessary information.