Quantify the value. This is part of an effective sales process. During your investigation identify what they're trying to improve - sales is an obvious one but business value can be assessed to be things other than increasing revenue. Other examples: improving efficiency/operational cost by reducing overhead or making a process more efficient so that resources can be reallocated to other parts of the business, improving margins, expanding the addressable market through product changes or other avenues, etc.

The key is being able to quantify the change/goal. If it can't be quantified it's probably not worth your time or theirs, seek something that is. Once quantified you can price it based on the value you'll deliver. They can make the decision based on whatever they want to use to assess its cost/benefit but it should be obvious and a no-brainer if the investigation was through.

If you're stuck in pricing things based on your costs or dealing with individuals who can't articulate/quantify their pain it might be best to seek other opportunities.