Is there a site that sells interior replacement parts? I recently bought a 94 Pontiac Grand Prix SE and need to replace a few things

Air Condition Knobs (One was missing, I replaced it with a crappy one for now)
Headlight Knob (Mine is incredibly dirty)
Automatic Shift Stick (Dirty and has paint chips)
Cruise Control/Windshield Wiper Stick (Dirty and has paint chips)
Front Right Automatic Window Control Protector (Cracked)
Entire Plastic Dash Board (Many paint chips, but only on the plastic, not on the vinyl)

Also I'd like to replace my my tape player with a CD player, is it possible to get a reasonable priced one that came in the special package?

Junkyards,
dealership...

I think some of your best bets are either jukyards or dealer ships. Or try some catalogs. I nkow JC Whitney carries interior peices, check to see if they make some for your vehicle.