Based on your criteria I would recommend the G&G CM (Combat Machine) series. They're polymer bodied M4's that perform quite well out of the box, best gun at your price range IMO. They come in several different styles, from traditional style M4 w/carry handle to a MK18 MOD1.

7 inch to 10 inch m4 would probably be your best bet in that price range. Most options available for gun choices and upgrade parts, as well as easy to manipulate controls in close quarters.

Suppressed KWA MP7 - hands down