The dish I always take is Shish Taouk which is charcoal-grilled skewers of marinated chicken cubes served with a delicious garlic sauce. The cost os most main courses are around 12.95 GBP, which is surely not only the cheap side, but I believe worth it.
The food comes and fast and the service is very quick. So perhaps not a place for a romantic dinner, but rather a more elegant fast food place.
21 Edgware Road
London
Tel. 020-7723-0773