Princess Auto sells a multimeter with a thermocouple readout on it. Reads a K type thermocouple, check ebay, or run the wires through a piece of stainless tube, crimp them in place at the ends, and have a welder buddy run a quick bead across the ends to fuse them in.
I split the wires and crimped them in to the opposite corners of the squashed flat tube, then TUIG welded them. Reads only in degrees C, but used t go on sale for $10. Just gotta remember to turn it off afterwards or you go through a bunch of 9v batteries...
Or go right flash and look at the digital temp controllers at Auberin.com, and either use it to control your pot, or just wire it to a power source and use it as a readout.
Cheers
Trev