Belfry Bat Detector: Hand built to order, an assembled unit that is portable, small, lightweight and is powered by a 9 volt battery.
Bertrik's bat detector page: Information on building your own bat detector
Convergence Technologies, Inc. (USA): Bat detectors
Laar Bioacoustic: Sound analysis software, highspeed harddisk recording (ultrasound)for bats,dolphins,grasshoppers up to 500kHz sampling rate,multi-channel solutions,bat detectors,microphones,monitoring system
Pettersson Elektronik AB (Sweden): Bat detectors
Stag Electronics: Bat detectors, books and CDs of bat echolocation, downloads of bat sounds and bat music.
Ultra Sound Advice (UK): Various ultrasound devices (air ultrasound, bat detectors, and data logger).
Von Laar Media GmbH (Germany): Bat detectors.