I am sure this is a bit late now (been away from the forum for a time). Yes, most things are priced in euros and the last thing they want is their own currency BUT seeing as our currency here is tl (turkish lira), we only took tl. They will take it but make sure you know the days fluctuating exchange rate AND always barter! We have never paid the asking price.
We visit Turkey often as it is only a half hour hop over by plane and they are lovely people, so hope you enjoy your stay. If you can learn a few Turkish words all the better, they love it if you try.