You should also keep your eyes open for older RGB computer monitors. What you're looking for is a monitor that accepts separate RGB signals, and supports a 15.75khz sync rate, which is the same as NTSC. Many older computer systems, such as the Atari ST, Commodore Amiga, and the Apple IIGS used RGB monitors like this.
Another option, is if you can get your hands on a European television set with SCART inputs. I don't know what kind of video standards Pakistan uses, but in most of Europe the SCART connector is fairly common on televisions, and that provides analog RGB inputs, and many sets support NTSC framerates. It's possible to use one of these for an arcade monitor - you just have to build a simple cable.
-Ian