If you have an AR-type rifle, you could score a 9mm upper receiver for that kind of money. If you don't own an AR, a Ruger Deerfield (.44 Magnum), or a Marlin Camp Carbine would fit the bill. The Camp Carbines come in 9mm and .45ACP, they take *&* and 1911 magazines, respectively. The Deerfield only comes with 4-round rotary magazines, with no other caliber or magazine capacity available.
Also, Ruger makes the PC-9 and PC-40, which cost around $400 and take standard Ruger 9mm and .40 pistol mags.