Thermocouple wire is cheap but the meter to read it 
isn't.  However, you probably have a digital multimeter 
that reads millivolts.

So grab a piece of thermocouple wire, and at each end, 
twist the leads together (hard solder them, 
preferably), then someplace in the wire, cut open the 
jacket and cut one of the wires.  Connect the 
multimeter leads to these two cut wires.  Now glue one 
twisted end of the thermocouple wire to a cheap 
thermometer's bulb.  Fasten the other twisted end of 
the thermocouple wire to the spot you're trying to 
read.  Go into the appropriate approximation 
spreadsheet and read the temperature.

Choices of thermocouple pairs:

Type J - good for high temperatures, easy to solder, 
sensitive to getting wet

Type K - good for higher temperatures, somewhat more 
difficult to solder, sensitive to flexing of the wires 
from vibration

Thermocouples generate a voltage according to their 
temperature.  If you join two thermocouples together so 
they buck each other, you can read the difference 
voltage.  One thermocouple is kept at the reference 
temperature, and the other is fastened to the object of 
interest.  That's what the above setup does.

NIST chooses 0C for their reference temperature and 
assigns 0 volts to that temperature.  All other 
temperature-voltage entries are referenced to 0C and 0 
volts.