I have a home embroidery machine. I have done small jobs: names, initials, logos. This is on fewer than six items. With the type of machine I have, it takes a long time. Customer would bring the goods and I would do the embroidery.
If you are serious about doing hats and such, you would be happier with a pro machine. These can be had for $10K or so. I will tell you that the money is made in selling the "blanks" (shirts, hats, etc.). The only model of doing this without a storefront that I have seen was a guy who traveled to alpaca shows and embroidered hats, shirts, and such on the spot with farm logos etc. I think animal shows of any kind would be a place to do this.
My embroidery business was in conjunction with doing alterations and window treatments.
Hope this helps a little.