I think what kills it is that the demo looks terrible. Sorry, it does. It looks like some of the stuff that came with blitz.
If you want to sell it, I would make a demo that showcases the features in your code. People aren't going to buy it on faith. They want to see the features in action. From what I can see, I don't see anything there that couldn't be done from scratch in a short amount of time, but there may be a lot of stuff you've made that just isn't seen in the demo.
As for the price, $20 is cheap, but then again, if the code is useless you just lost $20.
If you want to sell it, I would make a demo that showcases the features in your code. People aren't going to buy it on faith. They want to see the features in action. From what I can see, I don't see anything there that couldn't be done from scratch in a short amount of time, but there may be a lot of stuff you've made that just isn't seen in the demo.
As for the price, $20 is cheap, but then again, if the code is useless you just lost $20.