Building your own signal amplifier for an RTD is not very expensive, nor vary hard. Essentially look up "Wheatstone Bridge" for the details, but 2-9V batteries and 50cents of resistors can create what you need.
The abstract is, an RTD is just a fancy resistor that changes resistive value based on temperature. Using a voltage source, and three other known resistors (choosing the resistance value takes bit of thought), a proportional voltage change can be sensed on the RTD. Based on how the resistors are selected, the sensitivity of the system can be changed.
I set up something similar using a load cell (resistance varies with weight), so that I can measure how much water is in my kettle, and track boil off rates or monitor sparge water rates.
I am just guessing, but if it is a 1kohm RTD, then you would put the two 9v batteries in series (giving you an 18V DC power source) and choose three 1kOhm resistors for the other devices. If your RTD was scaled 0-1000Ohms equals 0-300F then you are looking at a sensitivity of about .0165V/deg F. By choosing a more sensitive RTD or varying the resistors, that can make things more sensitive.