|Not actual brooder.|
Contrary to popular belief a brooder box for your chicks/turkeys/ducks does not have to cost you much, and even if you aren't handy with a hammer you can still build one quite easily. We used 2 free pallets, 2 2x4x8 1 2x2x8 , 1 1x3x8 1 sheet of plywood or OSB, chicken wire, straw, nails or screws.
Cut pallets in half with skill saw or chainsaw ( it can be left uncut but then you need 2x the pallets and the box will be taller).
Take 1x1 chicken wire and line the bottom of the pallet. This should leave a 4" gap or so between lumber and chicken wire. A staple gun works great. Stuff with straw. It will block all the drafts and also insulate your birds from the cold. DO NOT be stingy with the straw. Pack it in until it won't hold any more.
Attach all 4 sides together using nails or screws. Pallets works great because they are already framed but sometime it is difficult to get your drill/hammer into such a tight place so you can take (2) 4' 2x4 per side and use on the outsides (top and bottom) making sure that you screw/nail into both pallets (I used 2 rows of screws about 2 inches apart wide and 1 inch for high spacing) use 4 nails/screws per corner - four corners per side.
Attach (2) 4' lengths of 2x2 onto the Edges of the top of your box. (Opposite each other).
Attach your 4' lengths of 1x3 on top of 2x2s - this should leave a 1" lip on top above opening. Slide 1/2 sheet under lip this is now your sliding top/access. It can be opened enough to feed/water or all the way and you can step inside for easy access. Please note: depending on your pallet size you may need to cut the plywood top down slightly to fit inside your "rails" under the lip. You can also use hinges instead but I found this worked best for us as we didn't need to do any extra framing.
You can attach a 1/2 sheet of plywood on the bottom for the floor. We successfully brooded 500 chicks last year with no floor just lots of shavings on the ground so you do not need the floor but if you are trying to brood them in early spring I'd use a floor. You can also paint it if you want. (1) 4x4 box costs less then $20 :)