Stan McDonald - Author of Error Coin Guides
My son and I search around 50,000 Lincoln cents every year (200,000 to date), looking for error coins, and this number is only for the last four years. Our search is part of authoring error coins guides. We have located over $3,000 in errors of all types which collectors have purchased from us. There are error coins in circulation, but patience and the correct detecting equipment make it possible to catch errors not easily recognized by most people. To date, our best finds include a counter-brockage 1995 Lincoln cent which sold for $80, a large die cud with three layers sold for $60, and several hundred minor errors selling for under $20 each.
Although some numismatists regard missing numbers as a novelty, there is a market for Lincoln cents missing a whole number. I have sold many 199x and 200x Lincoln cents to collectors at coin shows for $5 each. I set up bins of error coins with pricing set at $1.99, $2.99, $3.99, and $4.99 filled with die errors, striking errors, and planchet errors. I also sell higher-end coins and error coin guides.
There is a market for filled letters and numbers and BIE errors. Filled letters, numbers, and BIE errors are primarily located in 1990s mintages. Occasionally we find a wheat cent with these attributes.
We have discovered a 2019 Lincoln cent DDO, now graded as NGC MS66, which we are holding back from selling until we can determine a fair market price. Recently we submitted a 2020 DDO error coin to NGC and will post the results once we get the coin back.
To search through many coins without using a 10x loop and looking at each coin this way, I have set up a slider, a microscope 10x, and a large monitor. The large monitor allows me to look closely at the details, and then I can enlarge the photo if I want to look closer. Some collectors use the term "spread" to describe a DDO and DDR coin. A widespread coin would be 1955, 1972, or 1969-S doubled die; a medium spread would be a coin with attributes of doubling with visible overlapping, and a low spread would be like 2019 in the photo.