Great! You have a base to refine your product till it's the cat's meow. There's nothing like word of mouth, better yet, references from businesses who've actually used your product and absolutely love it! You marketing effort should just be the product, but also real verifiable applications of your product. Put together a little marketing video where the existing businesses vouch for your product. <br> I agree with what #pbreit said as well. Once you have 30-40 mom and pop stores using your devices, not only will you be more confident about what your sell, your potential customers will be too. See if you can target small but high traffic businesses, even if it's lunch truck or a no name pizza joint at a Campus near you. </br> You've got a great idea, simple and potentially very effective. Iron out the kinks before other competitors get to market. Once again, best of luck!