I would be attending trade shows where retail store owners can see the boards first hand. Another option would be to utilize LinkedIn. Business owners are far more likely to accept a request from you to stop by and chat on LinkedIn since they can see your profile and validate what you’re all about.

First contact would be to build the relationship if you stop by the retail store cold. You don’t need a yes or no from them on if they’ll carry it on the first meeting. I would get to know the owner(s), their story, what makes them select a product / service, current pain points they face with other suppliers (you then use that to your advantage), and then describe your line of products. I wouldn’t take up too much of their time on the cold meet. My goal would be to get a scheduled time outside of store hours where I can sit down with them, bring a sample or two and then discuss pricing, delivery, warranty, etc - all the technical stuff. I don’t think I would talk pricing on the first visit unless it was a product or service that was sold mainly on price such as readily available consumables. If I was selling mops to a cleaning business generally all mops can do the same job. They would be heavily focused on price so I would go in asking what they pay per mop head and saying I can beat the cost.