Tell me more about what you are looking for. I'm not positive I understand your question - but if you are looking for a way to TARGET those SMBs with ads and gain them as customers, then this is my answer:

We had a TON of luck by targeting them on facebook ads. Depending on your budget - there are millions of them in USA alone. The targeting option that we set in the facebook ads platform was "Small Business Owners". It was one of the key ingredients to growing our SaaS application almost 400% this year.