cheap used parts? The salvage yard. Black and red sounds good, but I'd stay away from painting random pieces of your interior with red spraypaint (such as the vents, center console, etc). Black dash with random red spraypainted bits looks a little trashy. Black dash with red fabric inserts on the door, red carpet, and red Recaro seats, on the other hand, is a common (and good looking) combo.
SInce you're new, try looking at some of the posts in the "showoff 6th gen civic" section. You can see what others have done already and determine what you like and what you think is hideous. It's your car, but since these have been around for a while, good chance someone has already done EXACTLY what you plan.
Welcome to the forum