I'm retired from owning my own business. If this venture is to be your sole income, you need to reconsider the idea. Startup costs will be more than your budget, w/o machinery! Just the delay inherent in the costs that go into you product and getting paid will eat up more! I highly recommend you do this as a moonlighting gig first. Basic tooling & setup costs will be more than your machine budget. Wearing all hats means spending time as your salesman, secretary, accountant, janitor, all taking time. Are you going to stock materials? Is your customer willing to wait for you to order materials? Can you afford to buy in large enough lots to get some sort of a price break? Then there is the issue of managing workflow to keep a steady income.
+1
I had my own business for many years, not a machine shop but I was pretty friendly with the owner of a small machine shop in our town. I don't want to be negative, but the questions you're asking make me wonder if you're being realistic about the venture that you're inquiring about.
If you really want a machine shop to build the products you have in mind the best way to get one would be to buy a local business that already has the machines setup and operational. Buying hobby grade machines will probably be a waste of money, and refurbishing used machines to perform at the level you're wanting is quite unlikely for someone with a YouTube education.
If I were advising you I'd recommend starting with a decent lathe first, then moving on to the mill before getting a surface grinder. Grinding is only really useful when you've already made the part and heat treated it, and, it's considered a specialty. The shop I mentioned above actually rented one corner to a guy who only did grinding, obviously if they had considered it profitable to do themselves they would have made it part of their business.
Another business I owned sold trick parts for racing go-kart engines. We had machine shops that would do production runs for us and hold the stock until we needed it. There are plenty of good job shops out there that will be able to produce your designs better and for less money than you're likely to make them for.
If you want to make various products, without a serious business plan and investors, IMHO your time and money would best be spent on learning CAD and 3D printing. That way you can make prototypes to test potential markets, and contract out production once the design is vetted.
Of course I don't have any idea what experience you have in business, or machining for that matter. This forum is great because we have such a mix of dedicated hobbyists and seasoned professionals. Pretty much everyone will give you an honest opinion and do so in a polite manner. One of the most important lessons I've learned in half a dozen businesses over several decades is to make sure your plans are solid before investing any money. Also, having a good partner, mentor or consultant is invaluable because it's easy to think your plans are great if you don't have someone else to pick them apart.
I do machining as a hobby, maybe someday I'll have a great idea and make it into a business but the odds of that happening are pretty slim. I hope your ambitions are rewarded with success but believe me when I tell you that it's harder than it looks.
Cheers,
John
