So it's more like this: I make a product for 5 and sell it for 6. My production facility is maxed, but there is still much demand. So I (or someone else) sets up another factory, making them for 8 and selling for 9 (there is demand enough). Now, will I keep selling at 6? No, my prices will also increase (to maximise my profit), and the final price will be where the demand curve crosses the supply curve.

I am wind, the new one is gass. We both make the same product, we sell at the same price, but I make a larger profit.