I used to maker about 250 gallons every week when I ran a really busy steakhouse, sometimes closer to 300 at the busier times of the year. We had an Emery Thomson blast chiller and we had about a dozen different flavors plus a few sorbets. Those Emery Thomson blast chillers are the best machine you can get for producing it on a large scale.
Initially, I insisted on making my base from scratch and refused to even entertain the idea of buying a neutral ice cream base from a dairy. I bought the most expensive ingredients and made a mediocre ice cream at best in the beginning - it was grainy and icy and generally not very appealing. I looked online for some resources and bought the best book available by the industry expert, Malcom Stogo.
This is the book and it isn't cheap, but it's the best book to have, especially if you're not an expert already and serve it in a commercial setting: https://www.amazon.com/Ice-Cream-Frozen-Deserts-Commercial/dp/0471153923/ref=pd_lpo_1?pd_rd_i=0471153923&psc=1
I spoke to him a couple times on the phone and he talked me into buying a mix, which made a huge difference. Within a few days of starting the mix, the ice cream was a hundred times better. Buying a mix from a local dairy is really the way to go - you have the exact same butterfat content every single time and the timing on the machine is never different. And if you want a flavor with higher butterfat, you can just add some cream.
People never realize how expensive ice cream can be until they start adding ingredients into the base and watch the cost add up. Sorbet was actually the most expensive option we had, especially when we used fresh fruit.
I also have a PacoJet I use at home and you can make some pretty amazing stuff with that, but not on a large scale and you need a lot of expensive beakers for each batch. I actually refer to a PacoJet as an ice cream "finisher," not an ice cream "maker." And unless you have a blast chiller or liquid nitrogen on hand, it takes almost a full day to be able to actually spin the ice cream from the time you make it. But a PacoJet produces the best texture, especially for sorbet.
Whichever direction you go, don't skimp on the ingredients. Buy real vanilla extract or paste and make a point of trying not to use flavor concentrates instead of the real thing - people can really tell the difference.