At a distance of just 400 meters from the Hotel Kastanienhof you find the Flohmarkt (Flea market) am Arkonaplatz, each Sunday it attracts from 10 am to 5 pm.
Here you can acquire lots of jumble, retro-things, handcrafts, records and books. 

Arkonaplatz, 10119 Berlin ---- Sunday from 10am to 5 pm

Rambling to the flea market at the Mauerpark, listening to musicians and afterwards relaxing in the great meadow of the Mauerpark …
Berlin’s young creative folks and clever private persons sell here their showpieces to trendy people of the neighborhood. Retro-design fanciers are in the right place here.

Bernauer Strasse 63-64, 10435 Berlin -------- Sunday from 8 am to 6 pm

Art and Nostalgic Market
Right next to the Museums Island about 60 dealers offer from ancient household goods, rare books, coins, records and many more through to souvenirs of the former GDR popular among tourists. 
Am Kupfergraben , 10117 Berlin , Saturday and Sunday 11.00 am to 5.00 pm

Antique market and rag-fair at the S-Bahn station Ostbahnhof. Antique and collectors' market in a good order with selected good wares offered by about 120-150 dealers.
Erich-Steinfurth-Str., 10243 Berlin , between Ostbahnhof and the department store Kaufhof,
Sunday 9 am to 5 pm...

junk hall Wedding,
open to all jumble sale on more than 3.000 sqm, furniture, clothes, HiTech and many more as well as a market for special items.
Turiner Str. 25, 13347 Berlin Mo.-Fr. 10-20, Sa 6-20, So 6-17 

One of the biggest, most beautiful and oldest rag-fairs of the city.                                                                                    
Straße des 17. Juni at S-Bahn station Tiergarten. 10623 Berlin.  
Saturday +Sunday 10:00 am - 4:00 pm