Heater VS Temperature Controller vs Both

I have a hydor heater in my 29 gallon biocube and its running mid to high 80s, seems like the light is always on and the heater does not shut off, I was going to by an ehiem heater because they seem to have the most support, however if I got a temp controller it shut on and off the heaters to a specific temp even though the heaters should do that anyways. Advice on either new heater, or just a temp controller or both. Not looking to spend more than $40 on a temp controller if I do go that route, i was looking at inkbird.