Has Diyarbakir bus - Sanliurfa to Dogubeyazit
From our hotel, we walked a few meters to the public bus stop and took the "Otogar bus" to the city's main bus terminal - about 10-15 minutes from the centrum.There are indeed direct buses from Urfa going to Dogubeyazit. I think there are 3 of them mostly leaving in late afternoon and evening. We took the Has Diyarbakir bus line at 4:00pm arriving Dogubeyazit very early in the morning. Trip was I think 14 hours.Bus fare is TL45, which is very reasonable already considering that it's a direct trip - minus the hassle of changing buses.Just go to Urfa's bus terminal, they have representatives there.
