Depending on where you live, check local farms… especially dairy farms. You can find some decent used stainless steel around dairy farms these days at an affordable price, I just saw a long double wash sink that could be modified and made into one or two open fermenters… bulk milk tanks if you’ve got the capability to do large batches. The hardest part about large batches is the energy and size of equipment required for such a large volume. Good luck with your PABP. 