Conventions in similar fields/disciplines related to your venture where Funding is a Topic or Round Table.
Attorney's and Accounting Firms-especially those related to IPO's.
Bankers or Money Managers in some institutions especially those who manage qualified Investors.
VC's and Investment Banks who convene symposia-sometimes you can learn of these through their websites.
VC's with funds under $1 Billion (or less).or those who are Private Independent
Crowdfunding, Angel List
Authors of Blog's, Articles etc (especially those in renown or refereed journals, sites). Tangential but related industry leaders