I'd go cheaper... if you have some cardboard boxes lying around, I'd deconstruct them and tape them securely to form a corral inside the coop. Maybe 24" high and about 10-12 sq ft? That should be plenty of space for the first week or so, after which they'll be big enough to jump out so you'd want to remove it before they do.
You can compost or toss it after.
Feeder and waterer, the usual mason jar type that's common at feed stores is what I use. For 8 you might be able to get by with 1 of each, for 12 maybe bump the feeders to 2 (not sure as I only do 3-4 chicks at a time). Set them up on low bricks or scrap lumber to raise them slightly above the floor/bedding to reduce waste.
(Note I didn't bother buying a mason jar for the feeder, I let them sit in it if they want. But with 8-12 mouths you'll have a hard time keeping it full enough without the jar feeding into it so don't do what I did!)
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