I can tell you that you can easily over spend when getting things together. The main thing is to not rush into a purchase. Like starting out, you don't need a bench grinder and a hand grinder. A hand grinder can do everything a bench grinder can do. I am almost 7 years into my business and I still go to flea markets to buy hand tools. I only go to harbor freight for air nozzles and rubber gloves and crap like that. I bought a 60 gal air compressor off a guy that was selling off stuff. That was just a gamble but 400 dollars and it never blew up. I just changed the oil as soon as I got it. Go to used equipment dealers, they will probably have air compressors and you can get some knowledge there.

metal costs quite a bit, consumables (wire, grinding wheels, ect) get expensive, you just have to learn to manage what you have.

Remember, most tools can double as another or 2 separate tools can equal 1 expensive equipment. You will have to decide that.