What's the best cheap thermostat for homemade incubator?

[JaimeRoxMySox]

I'm looking for the best thermostat I can get for $20. I've seen some cheap ones but the temperature ranges 9 degrees. I need something good so the incubator wont need much monitoring.

 

[sunny & the 5 egg layers]

I use a wafer thermostat. It is very simple, and the temperature range is very good. I think you can only order them online though, I never had much luck finding them in my local stores.

 

[Sally Sunshine]

https://www.backyardchickens.com/a/incubator-incubator

This article shows the three types you can use