I picked up a PT100 thermocouple with a 4-10mA transmitter, seemed cheaper than the PT100 module for the LOGO!, i'll just have to see how accurate it ends up being.
Transmitter
I took some courses with PLC's and industrial control, i used to work building custom industrial automated machinery. One day i'll have my own shop so i can play around again, but as for now, between a baby and a salt water fish tank theres not much money left for playing