My brooder doubles as the isolation cage - had a wry neck bird in it for as long as 6 weeks before, and I used to break broodies with it too (though now we have a dog crate for that, since the birds generally like to hang out in the brooder when it's not used for brooding). As it was recycled from a portion of our old prefab it's more or less the same as getting a prefab for isolation, but with a much smaller footprint (a little over 2x4) which is fine for 1 bird temporarily.