The machine shop business is a very tough one to make consistently profitable. Even legacy shops with all their tools paid for have a hard time keeping the cash flowing in; typically it's feast or famine. Most shops shy away from one-off prototype work because it's expensive to do with a lot of up-front costs that the aspiring inventor clients don't want to pay. I'd suggest starting a new thread, something like "Why did your machine shop go bankrupt?" The answers might help you navigate the common pitfalls.