Roosters are easy to get since hens are more popular than roosters. Your best bet is to find a reputable breeder who has the type of rooster you want and see if you can get one about 5 months or older. If you research different chicken breeds online you can narrow down what you want. None of your chicks from him will be purebred but they will hopefully carry the better egg laying genes you want. Unless of course you want all meat chickens, then get a rooster from one of the meat laying breeds. Dark Cornish are nice for meat and the roosters are good at protecting the hens. You just won't get good egg layers from him.