Money had always been one of the necessities when it comes to promoting, every movement now needs payment.
I agree with some members' suggestions, social media outlets should be one of your targets. This forum too because you can interact with investors or those who are interested in what you are building.
I believe they have money enough for market promotions but what they need is to find an effective way to do that so they won't waste their money.
I agree social media is the best venue for promoting their projects but of course, it should be properly planned and let some influence work on it.
You can try by also bidding on the first page advertisements. I don't know what is the normal price now but I am sure it is not that expensive.
Signature campaigns are also a great help to promote, proven by old companies that stayed here. Just one click away from the investors in our signature and Voila! they are on your page.
It is indeed, this Bitcointalk is a huge forum already and it was enough to make their project become known to the community. However, if we are targeting more investors, we should maximize the use of the internet, not just in this forum only.