I don't even want to know how you tested the sensor from Sharper Image.
Anyway, do a google.com search for "gas leak detector" (try with and
without the quotes). You'll get plenty of ready-made products, but also
a number of hits to component-level sensors. Several are for a variety
of cumbustible gasses, with and without odorizers.
Also look up the UEI CD100A, a low-cost consumer-level detector unit.
Maybe you can hack into it.
Robots for Less at Budget Robotics: http://www.budgetrobotics.com/
Author: Robot Builder's Sourcebook & Robot Builder's Bonanza
Talk to a local utility that does any kind of underground vault work
(electric, gas, water, cable) They will typically have a guy that calibrates
their units and tests them regularly. A few kind words may get you an
unofficial test run.
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