Even if they had the promotional campaign running on bitcointalk won't grantee that they will get funds for the investments. Yes, if the service is good and trusted, people will come to know about it and use the service but still i doubt anyone would be willing to invest in the development of the project.
The problem is that if you do not have the investment for the startup's development and advertisement, it will be hard to find such investment online. I would suggest OP look for his family and friends as only they could be the ones whom can trust on OP and fund him for this project.
For about the promotion, of course there are different types of project that has come around here to launch a promotion but yet they didn't end well and it was result that some of them where scammers so people are very mindful with the kind of places they puts their money to trade.