There's a shop in souq waqif near the hawks shops. But those are usually a little professional grade tents.. it might need extra stuff to get it fixed and ready for a camp. Like ropes and ground holders. There's however a "coleman" easy setup tent that is being sold in carrefour and other competetors, whis is quite easy to carry, setup, desmentel and a lot of fun. But its light weight and material doesn't make it suitable of even medium windy days. 13 knots could give you trouble. Other tents in carrefour aren't as good I wouldn' recommend really.

good luck camping.