Let's also not forget that many of these "rare" and "hard to find" parts just simply aren't trading hands anymore. Many of them are being hoarded away by collectors or being used on restoration projects. With each passing year the cars and parts we all covet become that much older, scarcer, and more in demand. Can you blame a vendor for not having the same top quality original parts year after year? Hardly, especially considering everyone who's participated in this thread has something "good" they bought at Carlisle either tucked away on a shelf somewhere or bolted to a car they've restored. The bottom line is, there just isn't much "old stuff" to be discovered anymore, it's getting used up. The days of entire late 60's early 70's era cars being dismantled and being sold for parts are near over. "Parts cars" of yesteryear are today's "project cars" which only increases the demand for parts. The pickings are indeed getting slim, and it's certainly noticable at places like Carlisle where good vintage parts used to be everywhere, but it's not Carlisle or even swap meets in general that are to blame for the change, it's just the passing of time. Just like you don't find the good old parts in boneyards like you used to, you don't find them at swap meets anymore either. Be glad that Carlisle remains as unchanged as it does...it's still a great place to spend a day hoping you'll find that elusive part, even if the odds are stacked increasingly against your finding it.
As for the days of going to Carlisle to buy a nicely restored car at a proper market value...well that's another story.