Rather than paying to show ads, try posting in groups with members who have a strong interest in your product or service. Search for and join relevant groups and communities on LinkedIn and Facebook and try posting your blog content, information about your product, or a promotion/sale.
Keep track of the most responsive groups and return regularly with new content and responses to comments. Be sure to follow the rules of the group you’re posting in to prevent your posts from being deleted or marked as spam – if you’re not sure, ask a group admin. It’s a great way to show off your product while building influencer relationships.