Acoustic monitoring for locating wolf packs

We currently use expensive Wildlife Acoustics SM3s to triangulate the position of howling wolves in Yellowstone National Park.  But we want to be able to deploy large numbers of wolf detectors based on more affordable solutions.  I'll be at the Science Makers meeting next week in Cambridge talking about my current system and ideas for developing smaller new detectors.  If anyone has ideas and will be nearby, please come along!