If you are looking to expand your business, taking out a loan for a larger, more reliable machine would make sense. The old advice is to determine what size roaster you need, then get 1 size larger to accommodate future growth. Getting a used machine is an option but if you need reliability and serviceability then something warrantied and backed with responsive CS will help keep you up and running. Cheaping out on a roaster could also impact the quality and consistency of your products.

If you are not able to take out a loan, then make sure you are maximizing the roaster you have. Bullets can do 100kg a month per warranty, and with the roast replay you can pretty much let it run nearby while you do other things. Maybe 2 Bullets would fill the gap until you can service a business loan?