Every town should have a flea market. This one in Prague is relatively new and does not have the popularity of the flea markets in Amsterdam or Lisbon. However, as in any flea market, you never know what you will find. It is run by three people in the space next to the old industrial train station. And as many visitors can confirm, one of the main attraction is the guy at the entrance, mister Halada.
He will collect the entrance fee of 10 crowns (about 50 cents) and if you ask, he will explain to you everything about this place in the language you choose. You cannot miss him, he is operating on roller skates and uses his hockey stick for some reason I do not fully understand.
So, if you want to find something from the recent past, or the communist regime, or from the time when Czechs lived in the Austro-Hungarian empire, there is a pretty good chance that it will be hidden here in the middle of other junk and you can get it for close to nothing. And, if you came with too much of your own stuff, you can sell it right here – renting a spot for selling costs about 5 euros.
There are two other locations where you can find flea market (for location check the web site below), but this is the biggest one.