you can get a elegant but cheap ring in the souq. As for the romantic setting, like others say, you don't have to spend too much just to pop the question. Better go camping/picnic, under the moon, prepared all the food, if you know how to make a cake, put the ring inside (old school), small cake will do, then be creative, you know what you should do..

Goodluck mate!

Btw, prepare your speech/question. And dont forget on which part of the cake you put the ring. :)