Not to mention coins with very low populations or few number of pieces to sell every few years or decades, there is really no accurate price indicator, the price is set at auction when an example comes up to the hammer, the loosing bid is now the current market price for that exact coin. We all know coins aren't equal, not all MS64 look the same as every other MS64 as an example. The underbidder at auction didn't win, so are generally considered to be next in line to buy one, as it comes up for sale or auction again. If the wait is long enough and more collectors want the same coin again, the value will or at least should jump up in value and bids the next sale time. Coins such as patterns follow this usually, same for early very scarce proof coins (gold especially). Occasionally more modern coins fall into this through a low pop in a tough grade.
"Buy the Book Before You Buy the Coin" - Aaron R. Feldman - "And read it" - Me 2013!
ANA Life Member #3288 in good standing since 1981, ANS, Early American Coppers Member (EAC), Colonial Coin Collectors Club member (C4), Conder Token Collector Club member (CTCC), Civil War Token Society (CWTS) member, Liberty Seated Collectors Club (LSCC) & Numismatic Bibliomania Society member (NBS), USMex, Member in good standing, 2¢ variety collector.
See my want page:
http://goccf.com/t/140440