I saw your post saying you didn't want to take credit cards. I'm just wondering if you aren't possibly shooting yourself in the foot. You might want to consider charging a slightly higher price and offering credit cards, but also offer a 3% discount for cash. I don't doubt that your prices are going to be very good, but I think you underestimate the importance and convenience credit cards represent to the typical customer.
Just a thought. Whatever you do, I hope it works out for you.