It's the same in the UK, and I suspect the world over.
Want to buy a "Cool" image?, get out your checkbook and stump up lots of money for an E Type Jaguar, (XKE to North America), or a Lotus Cortina, a Mini Cooper S, or one of a select few ultra desirables. The old car hobbyists of more modest means choose to cherish and restore more ordinary fare.
Right now old American pick up trucks are commanding ridiculous prices over here, a while ago Mopar Muscle was the car to be seen in, who knows what will be the next desirable?.
There was a time you couldn't give away an Edsel, or a 1959 Cadillac, after the 1973 oil crunch anything with a big block under the hood plummeted in value. Try picking a good example for cheap now!.
And for those who look down their nose at anyone turning up in something not stratospherically priced, walk on by, go talk to someone who has put time and effort on a limited budget to bring their pride and joy to a show. You will find it mostly a very rewarding experience, and all parties involved will leave the show thinking "Hey!, I had a great time and met some real nice people today".
Roger.