I don't imagine the premia for something like this would be too terrible. My wife runs a business with a fairly high liability potential (horse boarding; man, if you think people get upset about risks to their negatives, you ain't seen nothin' yet), and even there, the price of insurance coverage isn't all that extreme. I would assume that processing film is a business much less likely to get you sued and with lower realistic coverage amounts.
Look into it in some detail before pulling the trigger on the project, really. Insurance isn't an especially fun-n-sexy aspect of running a business, but it's crucially important.
Have you checked into the legalities of that aspect? I don't know about Delaware, but in some places there are different hazmat regs for businesses than for private individuals. You might be excepted if the volume is low enough, but I think you'd do well to know that *first*...