Fast food
Al-Baik
Fried chicken- in jeddah, makkah and madinah, but not riyadh
Baak
Pizza thin crust and quite good, fried chicken, lasagna, sandwiches
Cheaper yet are the countless curry shops run by and for Saudi Arabia's large Indian/Pakistani/Bangladeshi community, which serve up large thali platters of subcontinental fare for under SR10. Just don't expect frills like air-conditioning.
Fast food is a huge business in Saudi Arabia, with all the usual suspects McDonalds, Burger King, Pizza Hut, Subway and not a few chains that rarely venture outside America elsewhere e.g. Hardee's/Carl's Jr., Little Caesars. Meals invariably served with fries and Coke cost SR10-20. Some local imitators worth checking out include:
House of Donuts
"the finest american pastries" - a chain started by saudi students who studied in america
Mandi
Chicken or mutton cooked with rice in a pot suspended above a fire.