Cost of Investor Acquistion
Creating institutional capital investment pools with funding portals is hugely important. Honeycomb Credit has trailblazed that with a foundation. You can go to pension funds, banks, insurance companies, credit unions, etc with these kinds of proposals. Point to HoneyComb's success story, differentiate your portal.
Side-note: would love to start seeing partnerships between niche portals.
If you aren't ready to do that yet, and are starting off with founders in your direct network, I would fill your relevant social media channels (that you send to people) with accessible and engaging demos of your product from the investor's perspective. Of course, content for business owners is important too... but think about it this way: fundraising businesses will be sending your social media content to their investors as to explain how the process is going to go.
Educational content on why your niche and portal serve a critical need. Explain to investors, why their investment is moving the country, world, or directly their community forward. Investors are in it for emotional reasons, this is crucial. This is also good content to show business owners that might want to raise on your platform. Feed two birds with one scone.
This is important, because right now - before some aggregator enters the market - funding portals are a sticky product, once an investment is made. As an investor, it will be bothersome for me to switch between portals.
Cost of Customer Acquistion
Firstly, deal flow. This is most crucial. Mark my words: outbound direct sales will be very hard.
There simply aren't enough businesses in anyone's closed network that are truly ready to crowdfund. You need massive marketing email lists that go to tens of thousands of people. You want partnerships with government agencies to send you leads. Partnerships with other tech services to put you in their email campaigns is also very valuable. Partnership between Wefunder and Firstbase is brilliant.
This is a loooooooong sales cycle. You want the user to sign up early, make it easy. If they've signed up on your portal, they are somewhere in the loooong middle of this funnel. They are going to spend a long time in there. You have to engage them, provide free webinars, community events, meet & greets with successful founders, consultants and lawyers.
Also, I'm open for business - hmu for consulting ;0