IIRC, Cops here in Baltimore use the Glock 22 (.40 S&W). I'd say buying a used Glock from a Police Trade in (Can be found for $~350) and taking a class to teach you fundamentals (sight picture, trigger squeeze, failure drills) will be very well worth your money.
Here: Linky
Firearms, Guns, Rifles. Grain Valley, Missouri. (Gen III Glock 17 (9mm w/ built in rail and better grip) for $389)