By advanced collectors...I meant those who have been collecting for quite a while. This series doesn't really offer much, it's similar to the Jefferson Nickel series when it comes to rarity. I"m not sure which remarks I have ignored as I have read every post in this thread. Plus, I also admitted that this series is valuable in both registry quality condition and some varieties (perhaps you ignored that remark): People who really love the Lincoln cent will find value in some errors and such or if they choose to collect ultra high grades. But, unlike most sets...there really aren't any valuable non-error/variety keys.