Whether you are putting together a price guide or anything to covey information, you must first determine what data you want to report. As I look at the American Eagle series, reporting prices is not the same as a price guide with grades across the top and rows for each year and prices on each row. It is not how American Eagles are collected.
American Eagle coins are collected either in their original mint packaging, also called their original government packaging (OGP), or graded by a third-party grading service and housed in a holder. Based on a quick, non-scientific survey, it does not appear that many people are collecting American Eagle bullion coins and filling holes in albums.
The first decision was easy. American Eagle coins struck for the numismatic market would be priced based on whether the collector had the OGP or not. While using the data from eBay to see if there was a price difference, there was a $10-20 difference for proof coins and an $8-15 difference for other strikes, like the burnished American Silver Eagle coins.
Many people believe that eBay is not a good source of data. Although there is a bias against eBay, the information learned by analyzing the buying trends from such a diverse market can tell a story. I will not base the prices on a survey of only eBay. The book will include a survey of dealer prices and other markets.
The first two columns of prices will be if the coin is in its OGP or not in its OGP. The rest of the table will have columns for graded coins.
Prices for graded coins have different considerations. At what point does the difference between grades become irrelevant? Using the eBay survey, it seems that the numismatic premium is significant for a 70 grade and lesser for 69. When the grade is 68 or lower, the average appears to be bullion cost plus a smaller numismatic premium.
Bullion coins do not come in packages, but there are other considerations. The U.S. Mint packs the bullion coins in special rolls that seem to affect prices. Rolls get packed in monster boxes for shipping to authorized purchasers. Those monster boxes also have a different price structure.
The problem is that the rolls and monster boxes have a limited shelf-life. Although there appear to be some rolls and monster boxes from previous years, most of the rolls for sale are from the current year.
One more consideration is that some collectible American Eagles are only available as part of sets. Sets in their OGP will be priced based on market factors while providing only the price for graded coins in the main tables.
For now, the price tables will look like this:
|1987-S||904,732||. . .|
|1987||11,442,335||. . .|
If you have another idea, please leave it as a comment below.