Hi
 
I would just like to add that raising a single chick on it's own and then trying to introduce it to an established flock is a recipe for disaster. Firstly, the chick will be lonely with no play mates which can lead to stress and depression and even health issues as a result and secondly, it will get badly picked on when you try to introduce it to the adult birds and have no siblings for support or to disperse the flack.
 
I would suggest at least 3 chicks, so that even if one dies, there are still two. If the coop is not big enough to brood in there, you may need to wait until the chicks are near adult size before you integrate and they would need to be kept within sight of the main flock for a week or so before putting them in together.
Alternatively, you could hang on, in the hope that one of your hens goes broody and then give her some hatching eggs. That way, she does all the work regarding incubating and looking after the chicks once they hatch, and because they have been raised within the flock there are no integration issues. Of course there is no guarantee that any of your hens will go broody but it's also probably extremely likely that one will go broody the day after you buy some chicks!, That's broody hens for you! They work to their own timetable, sometimes just to spite us I think.... You gotta love them though!