Are you telling me that you don't have a tstat? Not knowing what the difference between the two tells me you don't.
Thermostat= Device you plug the uth into that regulates the amount of power to the uth to produce the desired temp on the mat.
Thermometer= Device that monitors and displays the temperature of either the air or surface depending on the type of thermometer used.
Temp guns can be had on Amazon dirt cheap. Much less than $50. I would link the one I bought but its no longer available.