Ohio started selling medical a couple days ago. There are four dispensaries and they sold 8.7 lbs for a total of $75,000. So that works out to over $19 a gram or around $538 an oz. That's just crazy to me, but it's all about supply and demand.
As far as OTC weed. All I can say is from what I have experienced. The only "legal" weed I have purchased was out in Las Vegas last year. I got to say, I was not too impressed with what I got compared to what I have grown. I probably tried half a dozen different strains and they all were very similar. Similar taste, effect, etc.
So I think if you grow and sell, then all you really need is word of mouth. If you grow superior weed for a good price, people will find you. No advertising needed.