BLF special group buy for the Manker MC13 and E14 III can be found here [UPDATED M4D deal] Manker “EDC Muscle Combo – BLF Limited”
The Mankers should be pretty efficient and last quite a while with the Boost HL emitter as long as it is not always blasted on full turbo. Per manufacturer specs, the driver is constant current circuit (Non-PWM)!