So many sales proposals are fluffy. By fluffy I mean they're filled with details about (your) company, the features of your services or goods for sale. In essence, content that centres primarily around you.
Not the same as others
To differentiate myself from others, when I submit speaking or training proposals, yes I have testimonials, value adds from working with me and the norm. However, one item I include is quantifying their results from working with me.
How to quantify
You can do this by looking at bottom line results. Then quantify it. Their purchase will give them - what? More profit? More sales? More free time? How much is the free time worth to them? Show their rate of return.
This exercise is easy. Time saved?
Estimate the number of hours freed per annum multiplied by the value of that person's time. Quantify the savings in recruitment costs along with the productivity continuum.
Take the average value of one sale (you can even factor in the life time value of that one new client) multiplied by the number of new ones expected.
You can get the base information any number of ways. Research on the Internet. Their Competitors. Annual reports. Talk to HR professionals about salary levels. Colleagues in that industry. Allies within that company.