First off I forgot my camera so I don't have any pictures of the Quinke's Tube Birch built out of PVC and garden hose. It worked pretty well and came in under $30. Birch has decided to redesign it to only use PVC pipe. Without the need for hose fittings the cost should drop to below $20.
Our current one worked quite well with Visual Analyzer using only a computer speaker and computer microphone. This one is definitely being added to the bag of sound demos