Mission Possible/Bimetallic strip

Acquisition
Any digital device is likely to be using a thermistor or thermocouple to detect changes in temperature, not a bimetallic strip, so analog devices are your best bet for finding these.

Thermometers
The common rotary dial analog thermometers use bimetallic strips that are formed into a coil. One end remains fixed while the other end controls the dial's movement. The common outdoor dial thermometers, oven dial thermometers, and hopefully any other rotary dial analog thermometer should have a coil of bimetallic strip in them. Shouldn't cost more than $5.

Thermostats
Analog thermostats may contain bimetallic strips (more than one, potentially). There is also a good change that any given analog thermostat will use a mercury switch (mercury counts as a hazardous substance both in Mission and real life, so either don't even mess with it or be darned careful).

Usage

 * Heating - increasing the temperature of the strip is easy and fast.
 * Nichrome wire
 * Matches/Candles
 * Peltier device


 * Cooling - it is usually easier to cool the strip down to ambient temperature from a higher temperature
 * Fans (cooling to ambient)
 * Peltier device (active cooling)