Metro Grossmarket is similar to Costco. It is actually a German brand, that also carry the Makro supermarkets.
Metro is for businesses owners, you might be allowed to access to the store by using your Embassy’s account. There is a good selection of products.
You can find 3 Metros in Ankara, one you probably know by Nata Vega Mall in Mamak, one at the other end of Ankara, on the west side in the Fatih neighborhood, near Wonderland amusement park; and one in Etlik.
The bigger one is the one located in Etlik. It has 2 levels, and a wide selection of products, electronic, clothing, etc.. It normally has everything in stock, unlike the one in Mamak.
Tips & tricks for Expats in Ankara 