Taken together there are several conclusions:

1.  The top end of the market is again confirmed.  The best, rarest, most exceptional and beautiful material attracts bidders.  Images rule.  Prose, however early, important and wonderful is simply less appealing than letters from the author or their signed images.  We have entered the visual and connected era and prices reflect this. 

2.  The threshold between desirable and common is rising and this is difficult news for the middle market.  Ten years ago material that cost a thousand dollars sat upon the hinge point between highly collectible and common.  Today the hinge is higher.  What this means is that dealers are bidding for and acquiring ever more valuable material while stepping aside to let larger portions of the broad market fend for themselves.  For collectors of mid-level rarities we now know that AED valuation estimates are accurately predicting auction outcomes and the estimates are slipping.

 

As to why we are experiencing a decline in previously secure mid-level material there are several explanations and factors.

A.  When the market was rising between 1990 and 2006 dealers tended to move prices up across the board as important material set records.  It's now plausible that higher prices for much of the mid-level material were never justified. 

B.  Collecting of serious material is primarily the province  of the wealthy and there are, by all reports, fewer in this category.  The past decade has been for many difficult financially and what was, not so long ago, an entitlement of the upper middle class, may now have become an unsupportable luxury.   The evidence of strength at the top and weakness in the middle is consistent with this thinking.  The result is declining interest, and declining prices in the vulnerable middle market, particularly in the highly collectible but relatively common important books that commanded $5,000 or so not so long ago but which struggle in the auction rooms today.  This suggests an imbalance between copies available and interested buyers  at the epicenter of where most valuable books are found:  common rarities.      

C.  There are more options and competition and the economy is difficult.  The market is flooded with interesting possibilities.  Listing sites today display millions of collectible books.  They don't sell fast but leave the misimpression that many collectible books are common.  The more correct impression is that they have been listed for years and accumulated because buyers are rarer than the books.  For the collector the question should perhaps always be "why should I buy this?" because selling may not be easy.

 

My sense is that all these factors are involved.  Prices for many items went too high and now return to earth.  For baby boomers in particular the collecting moment passes.   An increasingly adversarial tax code and increasing longevity may also lead to sales of collections and liquidations of inventories.  As well, any continuing pronounced down trend in prices may induce further sales.   An orderly decline is logical while the market re-prices but the bias may be to the downside.