I want to get into competitive shooting and am looking for advice.

[BunnySlayer]

It's a bit of a drive but we're very beginner friendly. See my thread on the Tactical handgun match in Corona

[Gryff]

I recommend starting with IDPA for a couple of reasons. The courses of fire tend to be less complicated that USPSA/IPSC, and the round count at a match is generally less. That means that it is less overwhelming and costs less to compete.

9mm is a lot less expensive than 45. You need to decide how badly you want to shoot your 1911 vs. the G17.

As for holsters, you can get decent quality setup from Blade-Tech for $55.

http://blade-tech.com/Combo-Pak-Special-pr-897.html

It's not the top-of-the-line, but it's good quality and is an excellent setup for starting in the sport.