m9Frank... Good question. Have been tracking that for several years.
Seems to me that it depends on the absolute rarity, popularity, and current demand for posted issues. I am actually amazed as
of late to find that not only do the more desirable coins coins meet their posted price, lately some have been exceeding them. Short of the more valuable coins, I would say that your estimates are real close and on Par with mine. Nice to know that it is not just me. I am tracking similar numbers.
I attribute this to Teletrade,
ebay, Online auction houses, Investor Ignorance, and a healthy dose of of a very sick dollar.
I have seen some of this before. All that I can say is that I am not investing into coins as a store of wealth against a very sick dollar. To me that is Lemmings being led to slaughter.
I do not believe that the majority of issues being sold recently will hold their current values, much less show stable returns over decent periods of time. (ya might get short time spec wealth)
Most coins are not real good investment material. The ones that exceed expectations are the extremely elusive and difficult to obtain rare ones. They are seldom offered for sale .
All educated coin investors understand that for a coin to hold a store of wealth, it must have a fundamental reason to store value, much less to rise. Generally, that means seriously sick rare high grade gems that are probably currently out of favor with the lemmings. They are very hard to find none the less.
It always amazes me that the uninitiated seek the 1916D dime in gem full bands at the expense of other far rarer issues. That is a reflection of many years of mass marketing and investor ignorance. Those coins do hold some monetary value. However collector ignorance and investor knowledge keep their values well in check, relative to far rarer issues.
If ya wanna play... find the real rare ones. .....Gusp