If you want "cheap" then you should build your own, but definitely don't by cheap supplies to make it. You can get a broken fridge for free, then you just have to buy the stuff to go inside. Most breeders make their own because you can make really large, reliable ones for a lot less than a 2 clutch premade incubator. You are going to spend a fortune on a premade incubator and it won't be very large. Even if you buy a cheap Styrofoam incubator you are going to have to buy a nice thermostat, so it's pointless to spend money on a cheap one.

Trust us, we aren't telling you that you need to spend tons of money to be a breeder, but we are telling you that you need to spend enough money to keep the eggs alive. Of course it all depends on what route you want to take, go cheap and learn the hard way like a lot of us, or take our advice and have a smoother first year of breeding.