False. "supply and demand" only works in economic theory. In our harsh reality you have monopolies, combination of prices between vendors, even plain extortion. The average buyer becomes obligated to purchase for $10000 regardless of whether he can spend this or not, even though the market has only one buyer in a thousand able to pay $10000.
One example? On my country (Brazil), You can get government-subsidized loans with the bank to afford homes costing up to, say, $30000. Most homes here do not cost all that to be built, the majority could be sold at a good profit for let's say $10000. But what happens? Because people can apply for loans of up to 30000, then out of nowhere all the houses now cost at least that (but they actually cost much less than that). The result is that most homes are unoccupied, for those who can not afford them or who do not accept pay them.
(And do not take this as a personal offense... But for me the north-american mentality of "maximum profit at any cost" is a cancer that will wipe out humanity soon or later.)