This place has tons of possible fermentation vessels for larger batches. The ones of interest are the 15 gallon food grade buckets for $18, 55 gallon food grade barrels for $20 and best of all, a 275 gallon food grate tote for $90. Those are all listed as food grade but they sell other non-food grade containers as well. They even have 100lb and 250lb fiber barrels that could possibly be used for grain storage (not sure about that one though).
For anyone near Denver looking for larger fermentation vessels, this would be a great resource: