I'm not a collector but I am an appreciator of the hobby. I have been selling signage for 10 years and honestly what I see today is there is more difficulty in justifying the prices being asked.
Common signage has tripled or quadrupled in price because of pressure AT auction. People are using Morphy's and eBay sales as a gauge of 'value'. So you go to a show and a guys says to himself "Morphy sold one for X, therefore my sign is worth X." Or "Ebay has one listed for Y, therefore my sign is worth Y." Yet neither is true or valid. Auction prices such as Morphy's are well advertised auctions for individuals with deep pockets or narrow interests. The average early bidder is evaluating the signage or globe or can based on realistic value. The latter bidder and end bidder are paying premium prices because they have set aside realistic value for the desire to possess the item.
Ebay is similarly structured and is somewhat worse because it isn't limited by the size of the auction house or the call of an Auctioneer for a bid. And a guy in Timbuktoo who can't get a can that's plentiful elsewhere is willing to pay the higher cost of his desire to possess.
This has driven the perceived value above realistic value.
We all also can anecdotally reveal how many more signs have suddenly materialized at shows because it's profitable. We are seeing how much of a plethora of signs have been held back privately for years and years.
But there is a fight for a limited budget long time collectors have had to spend. Where 5 years ago they could spend $4000 on 10-15 pieces, now they might only be able to afford 3 or 4.
At some point in the near future a peak price is going to be reached for 95% of what's out there. I've already seen it start. New blood in the hobby has less of a budget and had been buying the lesser condition signs simply because they could afford them. But even those signs have become out-priced.
A few years ago I was one of only a couple regular sellers of sign at local markets. Now there can be as many as 5 or 6 sellers. That means less money in my pocket. So I've chosen now to avoid paying current wholesale pricing because my profit margin has shrunk and the fun of finding and reselling as a business has dulled. I now would rather take $800 I would have to spend on a single sign and spread it among 3-6 purchases which will garner me more money.
I know some may say, well a 'collector' isn't buying to make money. But there is an idea of again that realistic value of what is being bought.
I sincerely believe within the next few years we will begin to see a shift in prices to more realistic levels. As the short term collector finds out it's too expensive to add to their collection and shift interest.
The same thing happens in the vintage car market. A segment will increase to incredible levels, then the big payout buyers switch interest to something different.