There is an example of a purely unregulated market; EVE Online.
I play EVE. It's not a "very stable market". Goonsquad decided to attack miners in highsec. Mining is one of the main ways raw materials are generated for product generation, and when they did that, key resources to fuel starbases (oxygen isotopes, etc.) shot up massively in price. It would be the realworld equivalent of bombing oil pipelines and refineries.
As you get farther away from the main trade hubs and out into nullsec, prices can easily triple for commodities. And many alliances have policies to prevent anyone else from getting in on their lucrative cartels of freighter transports bringing needed supplies out.
But within EVE Online everyone is a professional trader, not some dude/mom/dad who just gambles some money on the stock market from behind his PC like it happens in the real world.
Like hell they are. Most people avoid serious trading because of the lack of easy access to information on sales volumes, pricing, etc, market volatility, and (unlike the real world) getting your products to one of the main trade hubs is risky. If blowing your ship to hell is cheaper than the cost of losing their ships to the police (concord), they'll blow it up. There's no jail in Eve -- in 15 minutes you're just like every other pilot again... and they'll loot your wreck and be on their merry.
I suggest that everyone plays EVE Online so that people learn about markets, about logistics, about profit per hour (just profit is for noobs).
And I'd suggest they play it to understand why government regulation and military protection of traders and merchants leads to vastly lower costs to society, and to see first hand how far the effects of market manipulation can travel.
And you're leaving out another critical component of Eve that isn't at all like the realworld: You're never sure who you're trading with. Identities can be traded, and because of this, and the interface mechanics, you can be buying supplies from your enemies one day, and selling arms to them the next.
And all of this "free market" love makes people incredibly distrustful, very manipulative, and economic power equates directly with military power. And what's more interesting... the distribution of wealth looks pretty much like it does in the United States: 1% controls over half the total wealth in the game... and that 1% can be very petty, self-centered, and short-sighted. Kings and kingdoms alike are created and destroyed every day -- there is no stability. In nullsec, you always have an exit strategy... a way to burn your assets and get out quick, because if the enemy doesn't fuck you over, your would-be kings claiming to be on your side will.
Eve is the wild-wild west, seen through the lens of a hundred spreadsheets. When it's a game, this can be fun. When it's real life... do you really want to go to bed one night and wake up the next with your house on fire and your neighbors looting each other, you, and everything else as the next Great New Power rolls in? Because this is a frequent occurrance in the game.