For one-offs, it would be more economically feasible to just mill the parts out by hand.
Coding for CNC is time consuming and not worth it for the buyer if they're just expecting one small part from it.
CNC has an allure because many same items can be produced almost identical to each other. You know your product will be same as the other guy's and if it works for him, it should work for you too. Great for mass producing goods in short time, but for one-offs, it does not offer anything that a skilled machinist can do by hand in less time.