There is a new model railroad market established regularly in Barcelona. It's held in Estació de França every first Saturday of every month. It differs from Masadas market in that it's exclusively dedicated to model railroading stuff, and not slot cars nor other hobbies.
That's their argument to say they are not competence for Masadas Market, but taking into account it's held with the same periodicity but exactly the day before, seems difficult to believe.
First of all the location of the market is perfect, inside the most beautiful train station of Barcelona:
You can admire the architecture and see also the trains:
Stands are inside the coffe shop / restaurant of the station, what means you can take a look to the offers with while drinking a beer or coffee, depending the hour:
There are just a few sellers, but prices are moderate and according to the market. There are no super bargains, but neither stupid prices for second hand models. It doesn't look like Masadas, where in my opinion there is a little Mafia selling second hand things at double price of the same article in new condition.
I don't mean all stands in Masadas are like this, they are just a few, but are destroying the reputation of Masadas market. I've had really bad experiences with some of them (not only particulars, also a very big and well known shop of Barcelona having a stand there) who lied me and sold me a second hand train assuring it was new. It was a series 800 shinkansen with no pantographs (they were assuring it was like that) and no stickers. I also see every time in Masadas some articles at four times its real price. And those dishonored sellers try to do it many times with Japanese trains because they can buy them at really low prices (Japanese trains have a very low price compared to Spanish and RENFE models), and trusting nobody knows about Japanese models sell them at incredible profit. But I do know about Japanese models...
So, good second option this new Estació de França market, small but in a perfect location, having the possibility to buy at fair prices (at least in the first edition...)