Customers clearly think that price matters. They are also concerned about risk. If the price is too low, the risk goes up. What they want are the features, but what they need is compliance with the specifications and anything they are required to comply with.
Your best clue as to which of these matter the most is the evaluation criteria in the RFP. Look at how they evaluate each item and how much weight they give it. Then make sure that your offering and the points of emphasis in your proposal reflect their priorities.
Risk is about trust, your approach to risk mitigation, and your past performance. Trust is developed through relationship marketing, demonstrated understanding and expertise, and transparency. Trust is important because people buy from people they trust.
But trust is difficult to specify or quantify in an RFP. This is the main reason why relationship marketing is so effective. So a risk averse customer will look at your approach to mitigating the risks (how well you understand what the risks are, as well as what you will do about them). They will also look at your past performance, since that is the easiest way to assess trustworthiness in an RFP. Keep in mind, when writing about risk mitigation or past performance, that the real underlying concern is trust.
What your offering is, will provide, or will do matters to the customer. They’ll study your list of features because that can be itemized, but what they really want is the performance, results and benefits that result from those features. They also need compliance, both with the specifications they have written into the RFP and with any other things (laws, regulations, internal directives, etc.) that they have to comply with.
When the customer assesses value, they look at the results or benefits of accepting your proposal, compared against the price. They also consider the likelihood of getting it at the price you proposed and whether you can/will deliver the benefits as described. In short, they consider whether they can trust your proposal. And they do all of this in comparison to any alternatives they may have (which can include doing nothing).