Can I buy a decent pre-made coop for under $300?
Welcome! Check craigs list, or friends, to find a shed or playhouse that might convert to a coop. Hoop houses are cheap to build (look in the coop section) but $300 won't come close to buying a big enough coop for your flock. If you live in a warm climate, a three sided structure is fine too. Nine chicks will need at least 2o sq. ft. of floor space very soon, and raise a huge amount of nasty dust your family shouldn't be breathing, so moving them out of the living room should happen soon. Your 'red rangers' are meat birds, who will be poor laying hens at best, and are meant to go into the freezer at about twelve weeks of age. If you have a garden shed, convert that. mARY
You will need four or five sq. ft. at least in the coop for adolescent and adult chickens, because they need a safe predator proof place every night, and when there's snow, or daytime predator issues. A safe attached covered run will also be important, for the same reasons. Re ranger type chickens grow slower than the Cornishx birds, but will still get very large, and many will have joint issues at least. They are also hybrids, not meant to live long or produce well. Mary