I am not breeding at the moment (next years plan) at least for me it represents a investment in time. I don't have a lot of free time so what I have is very valuable to me. The effort spent in breeding and having a successful clutch to then trust it to a home build thing just isn't worth it. The cost of building an incubator is really much higher than just materials

bits of hardware 10$ (guessing here)
Controller 100$
Time (2.5 hours guess again) $275
Testing time (1 hour) $110
Answer...
http://www.poultrysupply.com/reptile...php#juragonStd

This is just my rationalization maybe you have a lot more time than I do and really want to build things and fiddle with them that is awesome, I am jealous I simply do not have time wiring flexwatt is bad enough!