Here's some pics of my setup/poor man's fermentation control. The tub is from Costco, inkbird controller from Amazon, aquarium heater from Walmart, along with the fan. Temp is controlled pretty accurately and has really increased the quality of my brews.
Let me know if you have anymore questions.
One suggestion to control temps on the cheap that I've done is to place your carboy into a tub of water which helps to increase the thermal mass and then have a fan blowing on the open water to get some evaporative cooling going. You can also add a inkbird temp controller to control an aquarium...