Well Doozle, you failed to mention what you are looking for, engine compartment, exterior, interior.....whatever. As you said, there are a lot of parts out there for a Challenger for sure (of course not as many as there are for the Camaro and Mustang owners....but whats new, it was that way back in the day as well). And, as wp23n pointed out...when it comes to customizing...think outside the box (or web) and come up with your own ideas to make your Challenger truly yours. One of the best mods I have done so far was replacing the auto console plate with a manual boot. Not a "bolt-on" for sure, but easy none the less, and I got the idea from one of the other Challenger blogs. So you might want to try surfing this site as well as others to see what Challenger owners have come up with.
And, try looking at the first generation Challenger for ideas as well.....I have rear window louvers that were first offered on the '70 Challenger, and many of us have mounted '70 script style emblems on the front fenders just like the original Challenger had. (Of course Dodge is now offering this for the RT Classic)
Be original with your ideas and make your Challenger truly yours........