Experience in valuing packaging companies? Or buying accounts?

I am looking at making a small add-on acquisition in the packing industry. The business manages packing supply chain for customers with no real assets other than list of accounts that make decent margin for a standalone operation (8-10%). I am trying to understand how these businesses would typically be valued or traded on the market. Any help in the packaging space or other industries that similar business profiles (cleaning companies also come to mind).