Welcome and I hope we can be helpful for you here.
I'm in the middle of the country, so I can't speak of places around LA either. From my browsing online though, pelicanparts.com and bavauto.com seem to be the two biggest. Just ordered a few parts for really good prices from ddmtuning.com (and they've got a retail location in San Diego if you want to go for a drive).
And last but not least, you'll find out we're greedy for pics here, so if you can post some pics of your ride (you've got a photo gallery you can put them in), please do.
Justin