cocollectibles wrote:To do what John suggested, use Advanced Search and enter the stamp ID (e.g., Great Britain 33), then choose Closed Listings from the View Listings page. Using that example, I found 95 listings for those penny reds, of which only two of 21 auction items sold in the past 30 days, one being a plate 230 for $3.50; this is listed in Scott at $20 used.
But does that mean $3.50 is the "true" value of that stamp? No! This is the StampWants market value for that stamp, based on one item only, for the past 30 days. The "true" value lies with the collector, and if I were missing that one from my penny red collection, I might pay closer to CV if it was in great condition, with an interesting cancel, etc. but not even $3.50 if it was faulty or a worse copy than one I had.
IMHO, I do not totally agree with the practice of pricing store stamps in very good, MNH condition at anything less than CV; why undercut the market value ahead of time? Let the buyer determine the value by enabling "make an offer" and set a minimum percentage that you would accept for it. That way no stupid offers like 2c for a $300 stamp will be entertained. Better yet, maybe you'll take 20% of CV for that stamp, but get offered 40% instead! If you priced it at 20% to start, you risk losing the potential difference, decrease the "market value" (as closed listing searches reveal), and contribute to a spiral of diminishing returns regarding stamp values. But I think I'm not in the vast majority on this.

Peter, you hit upon several things here as relates to the stamp marketplace.
Collectors ave had it long established that the catalog values is not the true price of a stamp, even if the catalog states that the stated value is the retail value. This goes back to the old days when catalog values were an approximation and not a retail value. Dealers then began competing with each other by offering varying discounts fromcatalog value. This practice continues to this day. In business there is an expectation that is developed among the customers from this sort of practice whereby the sale price becomes the actual retail price. You are correct that for sellers it is a self-defeating method of selling as the prices can only go down.
This, in turn, has caused a rift betwen collectors and dealers. When it comes time for a collector to sell, the collector expects full catalog value for a stamp, but the dealer can only offer %5 to 20%, because the dealer discounts the sale price so heavily.
Not until collectors recognize that if they want to maximize what they can get from their collections when they sell to a dealer they will have to accept that catalog values are retail prices, and not until dealers end their practice of automatically discounting from catalog value (permanent sale) will this issue be resolved. Yes,that means never, and collectors will continue to grumble that they don't receive the fair value for their collection. Yet, the collector doesn't stop to think that they only paid a mere fraction of the stamps' values in the first palce, so their rate of return is probably actually the same if the collector does not consider the catalog value of the stamps.
People need to quit thinking that the're going to get rich collecting stamps. The act of collecting does not equate with turning one's purchases into profits. That is called investing, not collecting.