I agree with everyone else about the bedding. We bought some from a shop in Gunlukbasi when we first bought our apartment. It was great fun as the guy couldn't speak a word of English and thought we were asking for "sh*ts" instead of sheets! We eventually got what we wanted, but, one wash, and they were a mass of creases that just would not iron out. Take some with you from Dunelm - good quality and don't need ironing!
The Gunlukbasi road has a "cheap shop" that sells everything from hair colours, to screws and nails, to buckets and mops, to pans and cutlery! You can get everything you need in there and it'll probably be within walking distance for you. He will also negotiate a price if you buy a few things. Can't remember what its called but it's not far from the police station, but on the other side of the road.
As Scunner says, the markets are also good for household things, and very cheap. Enjoy your shopping and your new apartment!