Global growth advisor to companies looking to enter the $387 billion dollar online marketplace in the US, founder of Inc 5000 digital marketing firm, and author of The Web Guru Guide™.
I've worked with over 700 clients since 2001 to build, grow and prosper online. My specialty is helping foreign companies successfully penetrate both B2B and B2C markets online in the US. I advise entrepreneurs and businesses on strategy, branding, legal and regulatory navigation, website design and development, and post-launch management including content, SEO, social media and inbound marketing.
If you have a marketing budget (even $5/day will elicit much more response than you'd expect), there's tremendous untapped opportunity for your niche. Based on the description in your question, I think Facebook advertising would be smart, targeted and provide the best ROI.
Why?
1. It's simply the most cost-effective way to engage an audience in a specific niche like you're targeting.
2. It works great for B2C and B2B.
3. Unlike Google AdWords and other PPC options out there, Facebook makes it much easier for entrepreneurs and business owners to get started and manage campaigns.
4. Facebook is growing exponentially in terms of user engagement and activity on the platform. Your target customers are likely on Facebook and it's going to get more expensive to reach them as demand increases.
I'd recommend going to https://www.facebook.com/business/learn/ to get the basic knowledge you need to test a campaign. There are literally hundreds of other resources online that go into more detail on creating your business page, choosing audience and objectives, ad layout and other useful tips.
Hope this helps provide some direction :)