Are prices way down on classic muscle right now?

It's all about supply and demand.
Low supply and high demand equals higher prices, it doesn't matter if you are talking about diamonds or cars.
Then there's the hype brought on by sellers to consumers as a marketing strategy. Barrett/Jackson is a business first and a car enthusiast company second. For us enthusiasts, it has either wrecked the hobby or brought it where it needs to be. High prices suck for us working guys, but then again we are greatly enriched by the massive influx of quality reproduction stuff available these days for our cars.
20 years ago who would have thought that they were going to reproduce dart fenders?
So to answer the question, yes the prices are coming down to where they should be, but i will add, a lot more cars are being saved with the good parts reproductions available these days.
You can thank the big three in Detroit for bringing the prices down too, they saw there was a market for new muscle cars using retro names for big profits. It's hard to argue with what a new Challenger, Mustang, or Camaro will offer in terms of performance, handling, gas mileage, ease of driving, etc. versus the cars from the '60s and '70s, all with a warranty. All for about the same price as a resto on an older muscle car or less.