What most people refer to as peacocks are rightfully called peafowl. (Peacock is the name for the male of the species.) There are three types of peafowl: the blue or Indian peafowl, the green or Java peafowl, and the Congo peafowl. The blue peafowl generally makes the best pet, as it is more adaptable, tamer, and less aggressive than other types. The green peafowl is endangered. 

Peafowl require at least 25 square meters (or 80 square feet) per bird. This space is important in order to prevent disease, as well as fighting among the birds. Pens should be at least 2.5 meters (7 feet 10 inches) in height so that peafowl can fly and fan their tails. If you keep a male peacock, the pen should be large enough for him to display his long tail feathers without injury.
Peafowl have a loud, shrill cry that can aggravate neighbors, especially during mating season. You will want to make sure you have enough room that your neighbors can’t hear your peafowl. Peafowl are obviously best kept in rural areas.

Peafowl should have access to fresh water and be fed two handfuls of mixed grain every day. This grain can be purchased at most feed stores, and most game bird feed, like turkey, chicken, or pheasant feed, is also fine for half to two thirds of their diet.
About 5-10% of the peafowl’s complete diet should consist of peanuts or sunflower seeds, supplemented with green vegetables such as cabbage or kale. You can feed bread or fruit as an occasional treat, but never give your peafowl bones, as they may choke. Another option for a higher protein diet would be to include some cat or plant-based dog food.
Peafowl like to wander, so if your peafowl are free range, it is extra important to feed them well so they want to return at night and don’t go seeking food elsewhere

Adult peafowl are pretty hardy creatures but it is still important to do what you can to help your peafowl stay comfortable, especially since all types of peafowl originated in areas with warmer climates. This is particularly important if your peafowl was bred in a tropical climate.
Wooden roosts are the best way to shield them from the cold. If you are raising peacock chicks from peafowl eggs, be sure to keep them in a heated area for four to six weeks after the baby peafowl start to hatch. You should keep the temperature over 95º F and lower it by about 5º F every week.

Predators like coyotes, dogs, and foxes are the main concern for peafowl owners, especially those that are free-range. Tree houses are the best way to protect them from predators, and peafowl love to roost up high.
Wherever you keep your peafowl, make sure it is dry and warm, as muddy or wet conditions can cause disease or tail feather breakage. A large pen surrounded with chicken wire, with a wooden shelter or hen house with a nesting area, complete with a warming light, is a good example for a pet peacock habitat.

Peafowl need to be dewormed every two months. Products like Piperazine, IVOMEC, or Ivermectin cattle wormer can do the trick. You can also find herbal worming products at most feed stores.
You should also check your peafowl for external parasites like mites, lice, and chiggers. Since peafowl are not common pets or farm animals, there is no established vaccine schedule for them, but avian pox, blackhead disease, and coccidiosis is always a concern. Ask your vet on how to prevent and treat these diseases.
If you follow these tips, you can keep healthy, happy, free-ranging peafowl, and your life will be much more colorful. In some cultures these beautiful birds are even known to bring good luck!

Market

We could potentially sell the feathers to some of the fly fishing shops in the area as material to make flies for fly fishing out of.
Another option would be to use the peafowl as a "cash crop" by raising and breeding them to sell the offspring. I just did a quick search of the "going rate" for peafowl, and several sites get about $50 each for them. Selling little peafowl for $50 could be pretty profitable. Since the peahens will lay up to 12 eggs per clutch, a female peafowl would bring in about $600 a with each brood she hatched out, which isn't that bad. Since they can lay up to three cycles during a breeding season, by collecting the fertilized eggs things could become even more profitable. Also, each peacock can successfully mate with up to about four peahens...