I have a little cooler that I've been using. I've hatched gecko eggs in it, and it currently has some hognose and (accidental) corn snake eggs cooking in it.
A plastic cooler with a heat mat large enough to heat your cooler to the desired temp and a thermostat is all you need. I added a small computer fan to keep the air circulated so the temps will stay more consistent throughout. And, I have a container of water that covers most of the floor of the cooler. It acts as a thermal mass to keep temps more stable, and it keeps humidity up.
As a kid, I hatched some king snake eggs in a fishbowl full of dirt sitting on the dresser in my bedroom.