[swarmee]

Another point is to worry about the "minutiae" of the factory numbers. Some are exceedingly rare and other collectors care about them and will pay a premium for them. There was a big hubbub this year on eBay when someone listed like 40 cards from the Factory 30 series, some of which went for around $200 a common. It's possible these were cut off a scrap sheet from the printer because they were not supposed to be released. There are also some interesting cases where the factory was covered up, and another factory number was added above it. Those ones are called "Overprints" and also have a value bump.