In any company larger than a one- or two-man band, how much profit you can make the customer isn't going to be their primary concern.
Marketing author Seth Godin recently wrote about a hierarchy of business to business needs which, not unusually, hit the nail on the head. He provides a list of a sales prospect's concerns, and says that "in just about every organization big enough and profitable enough to buy from you, the order of needs starts with the first one and works its way down the list."
The list does not start with profitability – in fact, that one doesn't appear until number 6. In any customer company larger than a one- or two-man band, how much profit you can make them isn't going to be their primary concern. After all, they don't see the profit personally. Instead, they have way more immediate concerns, starting with avoiding risk and hassle.
So, if the first question customers are quietly asking themselves is: "will dealing with you make my job more secure?", you don't want to be leading off with "the product will save your company £10,000 a year". If that's your main selling point, then you need to reconcile the two. Use your product to keep the risk away. There's no risk in buying your product because you have such a good track record. If they buy your product, there's no risk of them losing their job next year because you're going to help them demonstrate how the product actually did save their company £10,000. And so on. The best salespeople do this without thinking, but for many of us in marketing, getting the right messages together can require a more considered approach.