Personally I think the best budget incubator is one you make yourself. It takes some preplanning and patience, but the results are worth it. For the same or less money, you get a better result in my experience. You do need to be building and "gadgety" handy, however.
If you are not, or fear such an endeavor is out of your scope, then one of the styro units might be your next best option.
If you go that way - pay close attention to #'s 7 and 8, below.
Some pointers for the would be DIY'er:
1. Use wood for the box. It breathes - one of the worst things about the styro incubators is their tendency to "drown" the embryos. Find some old shipping crate or what have you and use that. It doesnt need to be fancy, but you do want it to be thick (3/4") and sturdy. I insulate the exterior with bubble wrap and duct tape (not pretty, but functional ) and I paint the interior with gloss paint to about half the height. Hatching can be messy and this makes it easier to clean
2. Use light bulbs, overhead, for heat. you can use other sources but you only need to get to about 100 degrees. A couple of light bulbs can handle that and they are cheap and easy to obtain.
3. Use a recycled computer fan for air circulation. Any electronic device like a computer will have one. Keep your eyes out for a junker and remove the fan. Get a 12vdc wall convertor from the thrift store for $1 and you're in business. The wiring between the two is a simple two wire connection.
4. Make a floor 2" high inside the bator from 3/16" - 1/2" welded wire mesh.
Place stones, cermic tile, water filled bottles, etc. beneath this platform as thermal buffers, to hold heat.
Eggs lay right on this floor, just as they do in the styro models. I use the foam shelf liner stuff, but you dont need to. And I stopped "turning" eggs along time ago... I just reach in quickly through the opened top and roll the eggs around gently by hand.
5. DO NOT use water heater thermostats.
The controller is the heart of your incubator, so dont skimp. Buy a wafer thermostat or a reptile heater unit. The wafer switches can be had for under $20, the reptile controller for $25. THIS is money well spent.
6. Ventilation: 3, 1/2" holes either side on the bottom and two 1" holes on top. I use cut up credit cards, pivoted on screws as regulating dampers over the upper holes. I bore the holes with a common wood boring bit.
7. Monitoring devices: Get a decent thermometer and hygrometer.
I gave up on the all purpose, weather station units a long time ago. I also toss the junk thermometers that come with all styro incubators
I now use individual digitals, with back ups. This is also money well spent.
- My thermometer is made for aquariums and has a remote probe.
Cost? 5$ Obtained from
ebay
- My
back up is a childs fever thermometer - guaranteed to within .2 degrees accuracy.
Cost? $3-$4 Obtained from
WalMart
- My hygrometer is made for cigar humidors and so is compact. It also reads temperature.
Cost? $12 Obtained from
ebay
- My hygrometer
back up is a simple analog (needle) model.
Cost $3 Obtained from
ebay
- Water weasel/squeezie/water tube toy.
The temp probe goes in this, to simulate the actual egg temp. Air temps and egg temp can be different, so this mitigates that difference.
Cost? 88 cents. Obtained at
WalMart.
8. Read and undertand the concepts behind Dry Incubation, as found here:
https://www.backyardchickens.com/LC-DryIncubation.html
Dont be slavish about it, but
understand the concepts. Especially grasp how you control humidity by manipulating the vents. If you add water to adjust humidity, use a small tray in the chamber and just add what you really need. When I add water to the tray, I do it through the vent holes on top, via a tube and funnel.
9. MISCELLANEOUS
You will need some wire and wire nuts or buttsplices for some of the electrical connections. I use old lamp cord and the wire nuts are cheap. A few screws here and there will be needed and some common hand tools like, drills saws, screwdrivers, etc.
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It is both complicated and rather simple, if you plan this out. That is the key. Take it one step at a time, by gathering your supplies and tools before hand. Walk through each step of the project before you go on to the next. Patience and persistence are your by-words.
If this all sounds like too much for you, then I suggest you get one of the styros to get started -
again, read #'s 7 and 8!
Time is money and a purchased incubator may be better for you in the long run.