When I was in Budapest last June 2009, a friend and I went to few Turkish restaurants but to be specific; three restaurants. Two of it located in same area along the Szent Istvan road but the other one is quite further away and I can't recall the street name now.
Among the three, I would recommend to go to Szeraj that is along Szent Istvan. Although the price is slightly higher than the other two but believe me, it is worth what you are paying for. Not only the foods are tasty but also lots and lots of variety... appetizers, soups, main courses, side dishes and up to the desserts...
We had spent a total of HUF2,500 which is equivalent to GBP8 for our lunch. We had chicken doner with rice, chicken lasagna, potatoes mixed with mushroom salad and the Sarma; the rice mixed with spices and stuffed in vine leaves.
As for the Baklava and the Cacik; cucumber with yoghurt (minty taste), our afternoon tea break only costs us for around HUF1,200 (equivalent to GBP4).
Should I have the chance to go again to Budapest, I will definitely stop again at Szeraj besides trying out other restaurants.