Now I would suggest two things.
One - You should create content, distribute, and make connections in communities of your niche. If you provide compelling information, then people will spread the word for you.
Two - Hire someone cheaply (friend, intern, etc.) to help you with direct outreach. Make a huge list of your niche's communities (blogs, forums, etc.) and send each one a quick email. Your success rate will be low. It would be better to make connections with these people over time - so try to take it slower if you can and develop relationships before just asking blatantly for links.
Other quick win strategies like buying links, link swapping, and using software to spam will only get you penalized in the long term - so not really worth the risk.
Hope that helps!