I decided to make a "coolerbator" for my hatcher and it works great! I bought the biggest, most rugged cooler I could find (cost about $70), it claims to keep ice frozen for a week in the hot sun.. They I bought an STC-1000 for about $20 and a heating element from ebay. 2 large 12 volt computer fans and an old "wall wart" power supply from a cell phone (or something). I put the fans and heating element inside a hardware cloth cage at one end, mounted the sensor on the back wall and wired it all into a plastic box with the STC-1000. Holds temps well and I put plastic trays in the bottom for water. I have a set of 2 plastic lids just under the lid so I can open it without any air flowing in. The lids slide over each other so I can slip my hand in to remove chicks without dumping all the moist air out of the incubator, like always happened in a Hovabator.
It was cheaper, but more importantly, mush more effective than another incubator. If you want something less "do it yourself", buy a kit from incubator warehouse. The main drawback of a cooler is that the commercial auto turners never fit, but no turners needed for a hatcher.