I have an older very basic Hovabator, with no fan and no turner. I struggle to get it to hold a steady temperature.
I also just got a Exo Terra (reptile) incubator. It looks like a mini-fridge. I got it at Petland and they charge $299 for it. It has a fan, and you can set the temperature, and it holds it steady. It comes back up to temperature quickly after you open the door on it. It came with a plug in so you can take it with you or if the power goes out you could plug it into one of those battery booster things. I just put eggs in it the other day, and I can't wait to see how it does. oh, it doesn't have a turner, so I have to hand turn the eggs.