First, create so much value (efficiency, time-savings, cost-savings, happiness, whatever) that there’s no need to “compute” it. Make the so-called pay-back period less than a month. Change someone’s workflow so drastically for the better that they can’t live without it whether it’s saving money or not. Improve your customers’ marketing campaigns so obviously and drastically that they don’t need a spreadsheet to understand its value.
Second, price according to willingness and ability to pay rather than as a direct function of so-called “value.” The software development department has a budget for tools and different companies have different ways of arguing internally for expanding that budget — you have to match those constraints regardless of “value delivered.” The marketing department might be willing to pay for services but not for tools.”