How much coffee do you plan to sell?
And how much do you plan to grow in the next ten years? I know so many roasters who buy tiny ~1kg roasters as the started roaster for their business, usually because of the cost or because they plan to roast high quality small batches, keeping the coffee fresh. When I ask how do they plan to make living with a ~1kg roaster and if they did any profitability calculations the answer is usually “I do not know” and “no”.
While roasting is lot of fun, you do not have to be an entrepreneur to enjoy it. But if you do decide to start a business, treat it as a business. Have a rough idea of how much you need to sell in order to make a decent living, and how much you plan to grow in the next ten years. Buy a big enough roster that in the beginning you can roast once or twice a week, which can slowly grow into eight hours a day and seven days a week, but by then you will have a dedicated roasting team.
I think this is much better strategy then low-balling your expectations with a small roaster and upgrading every x months. The price difference between a 1kg and a 5 kg one for example are not so big, but the output is dramatic for your business. In case of budget machines like Garanti, the difference between 1 kg and 5 kg is $2,000 (information kindly shared by Garanti).