As your question is complex, and requires data to target new companies, here are 3 strategies which could give you start in targeting:

Here are 3 concrete strategies:

Strategy 1: If you have first/last name, City, zip code, street, phone, then you can create a CSV list and upload the data to Facebook Audience, then you will be able to target those specific people with Facebook Ads.

Strategy 2: If you have the company website, upload the company websites of the target companies to Linkedin, choose the Job Title position you want to target, and Linkedin will show ads only to those companies, and to those job titles.

Strategy 3: If you have the domain of the website, you can create generic emails such as Info@company.com, contact@company.com and send your proposal to them. Generating generic emails are legal as they are not connected to a specific contact.

To implement this 3 strategies, i presume 300$ will be a good fit to start with, if you want to target just a city. Also dont forget to create a landing page too.