[Oxforddan]

Are funders simply suppose to throw out an offer based on numbers? (Most funders do to get the deal and take a look at it) Would it be wrong to do some of the work upfront to give it a decent offer?

Your point is valid. Bluevine isn't a funder though. They are a "tech company" who just happens to lend $ as their product. At least that's how they describe themselves.