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 :)