Beating the deadline for the submission of the written RFP may create the impression of responsiveness. Showing up 15 minutes early for the oral presentation and staying within the allotted time will show that you are punctual and organized. And never try to blame your tardiness on another important client engagement. And never fail to respond or show up for the presentation without offering a cogent business reason why you've declined to participate. That will get you deep inside their business mind, and get you much farther than arguing why they should hire you instead of the other guy.
Most businesses have standard models to justify the cost of a project.
Ask and you shall receive. Ask the decisionmaker which models they are using to cost-justify spending the money. If you don't have exact data, get the buyers to agree that your educated guesses are sufficient. Act like their partner not like a vendor. The shift to the preferred supplier model and partnering with outside sources of supply is now the norm in sophisticated businesses.