Raising pheasants for sustainability, really isn't feasible!...unless your gonna 'go big'.
As already mentioned, cost of enclosures/facilities, feed, medications...if necessary, factor in 'losses', cost of chicks or eggs...then plan on losing 1/3 to 1/4 from various causes; accidental, diseases, and other, then the 'cost' may out weigh the return.
I raised Bobwhites on a commercial scale, around 5,000/year. It wasn't for sustainability purposes but as a business. Most years I did ok, some years, not so great. One year in particular, my entire operation was nearly wiped out by disease (UE) Ulcerative enteritis, before I got it under control.
I'm not saying it can't be done, just that it might be better to choose a different species of bird....for the reasons above and what others have mentioned in this thread.
HTH