Pricing newly-cataloged certificates

My database holds a large collection of certificate sales prices, but I do not have any indication of actual selling prices for about 19% of the certificates listed in the database. It is fair to ask why I don't have prices for all:

• I cannot possibly record every sale that takes place.
• Most collectors do not report their purchase prices to me.
• Dealers NEVER report their sales prices to me.

Worth or Value — Most collectors, especially those new to the hobby, want to know what their certificates are worth. I cannot possibly say what certificates are worth.

• Worth is determined at only one instant in time.
• Worth is the amount established at that one fleeting moment when the commitment to buy is agreed upon.
• Before or after that moment, worth is merely potential worth. 

Price — I estimate the prices collectors will likely encounter when buying certificates from major professional dealers in the United States. 

It is important to understand that price exists independent of worth. Price is usually the amount that sellers want for things. Owners establish prices all the time, but those amounts may or may not be the amounts that buyers are willing to pay. Prices may not necessarily reflect what owners are truly willing to sell for. If owners and potential buyers negotiate selling prices, then at the moment of agreement, they establish worth or value. After that moment, both sides may rejoice or regret. But at the moment of agreement, they agreed on worth.

Rarity — With only occasional exception, collectors believe that rare items are worth more than more common items. It is true that many collectors desire rare things and they frequently pay more for rarity. But I want to be very clear about this. Just because something is scarce or rare does NOT necessarily mean it is deserves higher price estimates. For example:

• A unique example of a superbly-engraved American Bank Note Company certificate will almost always outsell a unique one-of-a-kind generic, lithographed certificate by four to ten times. Twenty times is not unusual. They are both equally rare.
• Nicely vignetted certificates from the 1890s will almost always outsell much scarcer non-vignetted certificates of the 1850s.
• Issued certificates of practically any company will outsell unissued certificates of the same company, regardless of differences in rarity.
• On average, issued certificates and specimen certificates of the same company sell for about the same amount even though specimens are normally much scarcer.
• Preferred stock certificates normally sell for the same amount as common stocks of the same design even though common certificates are normally much more plentiful. 

There are no hard and fast rules for estimating how much the next buyer will pay for something. It is an unusual week when I am not surprised by either an absurdly high price or an abysmally low price. Experience suggests I estimate prices from these perspectives: