NOS: New Old Stock.
Things that were made a long time ago that are still brand new in the box or bag. BUT it has to be BRAND NEW! As in never used. If it's been used, even once, it's USED. It's not NOS
The good 'orgional' stuff! People will pay a high price for the orgional items and not OEM parts or parts just made to fit.
Example: you can get an OEM 1968 Camaro grill for $100 or so. Or if your 'lucky enough to find one', you can get the real origional grill for $350. Is it better??? That's not the point...it's the 'real' Chevie grill. Now for contests...that's very important to have the real part and not an aftermarket OEM part.
Many NOS parts and items are 'very rare' and 'very hard to impossible to find' so they command very high prices because they are the 'real thing'.