We tried a cheap forced-air incubator from Amazon.

All of these little rectangular boxes seem to have the same design flaw: the fan and heater are in one corner of the incubator, and the hot air blows out of one side of the box. So there are really hot spots in the incubator and relatively cold spots.

Since we had a bad hatch rate (1 of 8) with the thing, we decided to get a bigger, better incubator. After researching a lot of options, we got the Farm Innovators 4250 — lots of space for eggs, a centrally located heater and fan that blow air all around, and a humidity sensor (looks to be the same DHT-11 that we use in our sensor). We’ll collect eggs and get a large batch going in a few weeks.