Many companies offer mid to low four figure referral bonuses for referring candidates that are hired in hard to find fields like finance, engineering.

Perhaps you can pre-screen “long-tail”[1], high potential candidates and connect them with insiders.

You could give a portion of the insider’s referral bonus to the candidate to drive that side of the market.

Candidates don’t have to come out of pocket to incentivize training (if your candidates have a good chance of getting hired) as the insider will get paid by the company.

Different take on this idea. Maybe it already exists?

[1] edit: maybe not the right term of art here, but I mean under the radar candidates (non-ivy, good grades, good work ethic, etc.).