Visually it looks awesome, but what it really comes down to is the quality of the code. Most WYSIWYG editors leave a lot to be desired.
Second, I am always wary of amazing tools with unknown pricepoints. I get that you're still early, but some semblance of cost structure would be great. Frankly, I don't know if you're going to charge $1500 or $5 a month or free. I just don't know, there's too many ways you could choose to market this, and that insecurity, that lack of knowledge makes me uncomfortable.
That being said, great job on the concept and I can't wait to see what it looks like when it goes live.
Did you see the code output at the end? It looked like pretty solid HTML and CSS to me. What was particularly interesting was the adhereance to OOCSS principles in the styles, but that could just be the result of good practices with the user.
For a real demonstration why not try something more "real-world" and see how that turns out.
Let's see if it really works before we worry too much about price.
I personally spend $50/month on Adobe creative tools, and would gladly pay for better tools.
If you say it is amazing, he will probably charge $1500.
I guess the idea of a demo is to gauge interest, which will ultimately help in deciding price, among other things.