Back to the original question....I was lucky enough to meet a private collector(he's not on any forums) this weekend.....
he had a lot of NOS items ( things in bags, packages, boxes..never used, never opened or mounted )...
If he has this kind of stuff then others must do to and sooner or later this stuff will find it's way onto the open market ?
Even in the short period I've been collecting (2 years) I've got some NOS parts in boxes/plastic packs never fitted or opened.....I'm sure everyone on here will have some of the same as it comes with the territory.
On some level there are still lots of NOS parts out there but they are increasingly becoming the less desirable parts/colours and makes.