Glock 22 or 23, you can still find hi-caps for these guns at a reasonable price! The M22 is classified as a service pistol, being used for open holster carry. Although it is a large gun, you can still conceal it with proper carry clothing and holsters. The 23 is the perfect compromise between size and capacity. It came with a 13 round magazine before the ban but you can still obtain these through dealers and gun shows.
You would be very hard pressed to find such a simple, reliable gun that won't break your budget. Yes, there are the guns from HK and Sig but let me repeat myself, THE GLOCK WON'T BREAK YOUR BUDGET!