Ditto what Tim said.
Can I add that if you are interested in incubating (as POLwon't sit on them and maybe won't ever depending on the breed you get) there is the cost of a decent incubator and then all the things you'll need once they hatch. Heat lamp, somewhere to keep them etc.
Please also consider that incubating the first few times can have very poor results and often until you have gotten the hang of your incubator hatches are very hit and miss.
If this is the first time you have kept poultry I'd suggest looking into getting day old (or less than a week old) chicks and rearing those first. Still get all the fun of rearing them.
Then at some point in the future, if you still want to, invest in an incubator.
Please also consider going in, before you get any chicks or hatching eggs, what you intend to do with any cockerels. Most are never rehomed and often breeders will cull them early on or rear them for the pot. Once they start crowing and being around ladies, you will have your hands full. If you cannot home them and keep them you need a pen to keep all the boys so they are not around any girls. This prevents fighting.
Just saying the last bit as so often I see people get chicks or hatch without really considering the future and then when they have 4 boys and only 2 girls or something they have to deal with the harsh reality that they are probably going to have to cull them.
