Go to the used car lot at Al Aweer in Dubai there's loads of dealers, but be very careful some are quite dodgy and remember the old saying if it seems too cheap to be true, it normally is.
You might go to sharjah used market. some of cars over there are cheap. but it might not good condition. You have to be careful.
I more prefer al weer used complex. I know some friends over there. and I do always go there. you also can get some brand new cars over there.