I second Lordco for parts (especially since I know people there) but they are able to get a lot of items. Some speciality items you may be limited to online purchases.
KXWheels was mentioned for wheels and I will agree they have a large selection and are able to give good pricing however I find them to be very inconsistent with prcing and they have very poor customer service. If you deal with them make sure to get a quote elsewhere for the same product for comparison.
I ordered my rims.wheels from a place called Mothergoose Customs. It's in Langly and I have had a great experience ordering rims through them. They also specialize in Air Suspension if you ever decide to do that mod.
Oh and I believe LX stands for a type of "platform" used by Chrysler/Dodge. The Magnum, Charger and 300 are all based on the LX plaform. . . ther may be others also.
I just came over from LXForums. BCLX (our local group) has 59 members. We meet weekly. If you want more details let me know. As far as mods go locally...almost everything I have done has been bought from other members, or online. Don't worry tho...there are a million ways for you to soak an endless amount of money into your Mag! Every time I think I am done, I realize there is still so much more I want to do. Drop me a message and we can get you guys out to meet up with the local guys!
Tim
I'm in Langley and the best place I've found for any after market part is Mopac. They stock damn near everything and what they don't have they can get cheaper than most places.