ROI and sales projections.
Return on Investment is a combination of Budget and Sales Projections. You're only looking for $60k, so you may have found investors may not be the most sophisticated who may not know the difference.
The way I've seen Sales Projections:
A). Estimated numbers about types/generes taken from consultants and/or web sites. (Most know the numbers are worth about the same as the paper they're written on)
B). Comparative project numbers. Most know these numbers aren't that useful as most stats are padded with outliers.
C). Experienced, trusted Sales Agent estimates. An expert that learns about your project and makes predicts territory sales and the price range. Even these are taken with a grain of salt as there are so many variables outside your control.
If you're looking at choice A. Go to a site like filmspecific and pick up a subscription for a month for a few bucks. You'll find charts galore for various types of films and budget there. Choice B, google for a firm that does that or start contacting producers of similar films and hope they don't lie. Choice C. Talk with your investors to which sales agent whose numbers they will trust. Not all sales agent numbers are created equal. Some bump their numbers to pad their business expense account with your film.
I don't know your project, but generally speaking, if you don't have a name attached, you may be better increasing your budget get a B name or two.
Good luck.