I use past auction results most of the time and feel that gets me close to what the coin would sell for. Where do you look next if none of that coin have been up for auction in many years? Greysheet? I also look at what PCGS has the value at but sometimes that price is way high.
Initially what is the TPG price, then CPG. If nothing available: I look at what eBay sellers may have it listed for (if there is a match). Then if that is not available cost plus or some greater number. Takes some research see what similar material priced at. My last project won a 1917 world silver slabbed MS64 low pop coin for $30 online auc. Three eBay sellers had it at $125 avg. So that is my retail price for show / online. Nice profit margin, plenty room for negotiation / sweet. I buy low / sell high - That’s how I roll.
If it hasn't been up for auction in many years.... there really is no way to know! The best you can try to do is maybe look at similar coins (not exactly the same), with similar rarity which have sold recently. If it hasn't sold in years, than any price guide (PCGS included) is merely speculation. You may also look at trends in that series, again comparing similar coins to try and predict what the coin you are interested may be worth. If the whole series is hot or cold, that may help you trend from the last data point of that particular coin.
I find that doing a search for the coin and/or cert in multiple browsers can at times be helpful in uncovering obscure auction or dealer sale results that aren’t necessarily published. Google may yield different results than DuckDuckGo for example, so I just keeping digging and play around with different search engines/keywords, search the Stacks website, GC, heritage, Newman Numismatic Portal, etc. I may find nothing at all, but sometimes it’ll reveal something like a 10 year old Dave Kahn website listing with the sold price which at least provides a reference point to work from and compare the market overall from then to now in terms of adjusting to today’s value.
Often, using the trend pricing history from the same series may prove valuable, but that depends heavily on just how rare that coin really is. If it's truly as rare as implied by Larry's post, there are likely many collectors of the series who have lacked that single coin for many years. Independent of whether that series is hot or cold at the present time, such collectors probably would establish their threshold of pain based on the likelihood that another will appear timely. In Larry's situation, I'd look at auction history, and the frequency of offering. If the likely wait for the next acceptable example seems untenable, I'd consider past pricing less relevant than his passion to finish the set he is working on.
I also see if I can find an example in any grade and review auction descriptions as sometimes cataloguers drop helpful information about the availability, last sold, etc.
The last coin I was looking at like that was 1894-S Barber dime because my coin book has an empty hole for it and underneath it says 24 only. My 2023 Red book lists the last heritage auction in 2016 it sold for $1,997,500. If you are talking about a coin like that you have to put one in auction and see how much it goes for.
If looking at a six or seven figure coin (which I never will be), I would do what many people in those markets do and that is hire an expert or two to advise me. But I'm not one those collectors and my acquisitions and resources are considerably more modest. Nevertheless, I still collect some rarities that don't appear on the market at all often and for which the prices guides are entirely silent. Die marriage collectors of early copper, bust halves and other series know exactly what I'm describing where R-6 and R-7 coins only appear a few times a year or decade. The only way to get information is to assiduously research auction records and to dive deep into the market pool of your specialty. That means relationships with specialty dealers, specialty clubs and personal contacts among other collectors. Someone will point out the Greysheet now lists early copper by Sheldon number including some quite rare coins. Those numbers should be taken with a grain of salt and considered just one more data point among many.
Some good thoughts so far. Looking at every possible venue and comparing to similar coins in the series are likely your best bets. Otherwise all you can do is make an educated guess or send to an auction and let the market set the value.
How to put a value on a scarce coin. Sometimes you have to go old school - books and articles. If a coin is truly scarce/rare odds are somebody has written either a book or article on its particular series. And in there you'll find info on the coin's true scarcity rating as well as past sales results. But since many don't have the books and or articles about the only way others can gain access to the info is by asking others for help. This forum is often a good place to do that, so are other forums. Granted, even if you do manage to find the info, since it is old you still have to do a bit of guesswork. But at least you'll have a verifiable baseline to work from so that you can at least make an educated guess.
I would go in the Heritage site and see what they have gotten for the item. You can also go to PCGS "Coin Facts" which has the PCGS value, which are often on the high side, and results from major auctions. You also might find some leads to on-line offerings for the coin. I have used that now and then and even at shows. If the dealer has a table at the show, he may well have brought the piece with him.
Don't forget, folks. Just like there were students before there were teachers, there were prices buyers were willing to pay before there were transactions . . . references follow the action, they don't lead it.
I use auction results CoinFacts and greysheet. And make my own decisions like if a coin only had half a dozen auction records since say 2019. And half or more are details grades. And say i have an xf40 cac. Then I’m definitely going to ask and pay a premium for. If it’s a common coin I’ll just go with greysheet and average auction results. And then factor in eye appeal. Cac sticker. Originality etc. ultimately all price guides need to be considered in a coin to coin basis
If I was curious and there's no price guide to go by, I would just list it in an auction whether you want to sell it or not and see what happens. You can put an obscenely high reserve on it so it doesn't sell. Nobody sees what that is but if you get two or three people bidding it up, eventually you'll see what the market will bare. Remove auction. List it again next week or month and see what happens. It's not that difficult to list something and nobody is out anything. Start the bidding at one cent to get everybody paying attention.
