How do I prospect for broken link building 2017?

You can do it through a regular search.

For example: your keyword + links, your keywords + resources, your keyword inurl:links.

But, this is the hard way. Related Read:SEO GROUP BUY

If you're interested in going through a lot of sites every day, my suggestion would be to invest a great link prospecting tool like Dibz. Related Read:SEO GROUP BUY

Dibz is an advanced link prospecting tool designed to save you time, simplify the process of link building and influencer opportunities research. Suitable for both independent SEO consultants and full-service marketing agencies - Dibz provides the SEO community with an intelligent solution that greatly improves link prospecting outcomes.

Dibz will help you:

• Find the best prospects for both your various link building campaigns and influencer activations.
• Search, Sort. Filter. Cherry-pick opportunities you like the most and forget the poor ones.
• Get a list of email contacts to prepare your outreach campaign
• Manage your data using CSV
• Integrate your lists with Pitchbox for easier outreach

And much more...