I came across this Trane refrigerant monitor, it came out of a building being remodeled. It's practically brand new. I don't know much about the value of these but I've been looking around and it seems they are pretty expensive. Here's some info on it:

RMWG Refrigerant Monitor

This RMWG refrigerant monitor can be configured as an either self-contained unit or a split system (control module and a remote mounted sensor). Both configuration types can have additional sensing points added later on. This allows a system to grow whenever new ports or new refrigerants are required.

20 ppm sensitivity meets ASHRAE std. 15 and most local building codes
UL certification for fire and shock provides third party certification
Diffusion sensors (single channel sensors only) provide high level of trouble free operation due to lack of moving parts
Pumped sensors (four channel sensors only) provide quick response to increased levels of refrigerants
Max up to 8 sensing channels gives user a choice to expand sensing points in the future
Up to 5 different refrigerant types (R11, R12, R22, R-123, R-134a) sensed at the same time provides flexibility needed to meet the needs of the most demanding applications
4-20 mA and 0-10 vdc standard output sends input to any building automation system
4 relays (3 levels of alarm and fault indication) activates alarms and building ventilating system in response to alarm signal
85 dB buzzer (optional 110 dB buzzer) standard buzzer (optional unit mounted beacon, and warning lights are available)

I'm actually not in HVAC, I'm a carpenter. I don't know too much about this item, so please let me know what you think and make me an offer.

I have it listed here:

there are pictures available on that site, and I can email more to anyone interested. If no one is interested, please point me in the right direction of who might like to buy it.