A couple of comments regarding the last few posts:
1) Prior to master set demand for gold panda, it was true that only the rarer coins got graded while bullion issues remained intact. Once master set demand started, the price for OMP or MS69 was identical and most dealers stopped submitting key coins for grading because you upside was tiny and omps are easier to ship or carry back to china. Non key coins that dealers wanted to sell on ebay, their website or other auctions still were getting graded to reduce risk on these transactions. I am more likely to submit 1992 1/2 OMP worth $1200 than 2002 1/2 OMP worth $4500, because 1992 1/2 MS69 is $1450 ($250 spread) while 2002 1/2 MS69 is $4600 ($100 spread). I am no longer convinced that only better coins are getting graded, with exception of 1985-1988, which rarely are graded.
2) Re-grading accounts for 5-10% of the population for grades below MS69 and the number keeps declining as NGC has been more consistent, the chance of upgrading a recent submission is close to zero. Also, US-based dealers typically turn in labels from cracked coins so those get removed population reports. I only look at MS69 populations so those number typically don't have regrades in them, because it is very rare someone will crack out a 69 pre-2003 coin to go for 70. So in terms of total graded population of a coin the regrades might only be 2-4% extra, since 69 and 70 are not regarded and they often account for the majority of the population report.
3) For modern Chinese coins, public auctions account for less than 1-2% of total sales volume, almost the entire market is private transactions. Of course, super rare coins and top pop coins might be auctioned 10-30% of the time. What you see in the auction is not always a correct representation of what a coin will sell for even the same day in different city. I can say with certainty that 1995 1oz MS66 will usually sell for 2K less than MS69. Auction results can be skewed due to shill bidding, buyer not reading the description carefully (I have done it a few times), protecting your inventory (bid up something above market value to keep the book value of your inventory high, similar to corner the market), 2 bidders that don't have a clue or too much money to wait to buy the coin in the future, unknown variety, shipping constraints (covid has really shown how hard it is to move merchandise across the country and world), and import taxes.
4) Sales prices posted on ebay are not true transaction prices, if I list a coin for $1500 and someone sends me a question will you take $1400, if I reply to them with a $1400 personalized offer while keeping the ebay posted price at $1500, when they buy it using the personalized offer link, the coin will show that it sold for $1500 even though the true price was $1400. This happens a lot so be careful when interpreting sold transaction price.
