I know little about finance, but i will give it a try for the seek of discussion
If we refer to free market as the market free from government regulation and all people have equal source of information about goods\service and equal chance of making profit according to their holding .
This market doesn't exist, even black market is affected by government regulation which lead to increase the price of item being sold, i mean the free market is about supply and demand control the price without external effect.

If i have to chose a market that can represent this idea, i will say

Creyptocurrency market

It have minimum gov influence, equal chance to everyone and the price mostly determined by supply and demand.
By the way good blog as usual @thecryptofiend