That is the problem with incubators. If you want good hatches, you have to spend the money. Sure, some people have good luck with the cheap incubators, and some have good luck with homemade.
People by the styrafoam ones because they are cheap, and can fit alot of eggs. But, if you have 40 eggs and only 20 hatch, is it really that good? Good in my opinion is 75% hatching or more, every time. Not just the first time, but every time. It seems that with the cheap ones, the first few times are the best and it goes down hill from there. I had them, and now I don't. I had the same experience as most people. First few times about 50% then Set a incubator full, and maybe get 15 to hatch or sometimes none. After a few times of that, I chucked them. I spent the money on the Lyon ones, and bought all off of
Ebay used, at half the price of what they normally cost and won't ever switch back.
I have a hatch going on right now that I could not have messed up worse on. Didnt write down when I set the eggs, and so a week later, I guessed. I left Friday for 4 days, thought they were supposed to hatch Monday, so I upped the humidity, and disconnected the turner. Came home Monday, humidity at 83% and still nothing. Tuesday still nothing. I candled, and decided they weren't ready yet after all. Turned the turner back on, reduced humidity. Now this morning, they are pipping so I shut off the turner again and reupped the humidity. I have 9 eggs in there currently. I havent ever had anything less than a 80% hatch rate. Last one was 100%.