Although it is likely that you will only ever purchase, get in change or even hold a very minute percentage of the Lincoln Cents ever minted, the No "FG" error and it is actually an Error and not a Variety, is probably more common than most believe! All of the Master Hub Dies, Master Dies, Working Hub Dies and Working Dies contain the Designer's initials and if only one Lincoln Cent for a specific date and Mint has the Designer's initials, then all of the other Lincoln Cents for that specific date and Mint that do not have the Designer's initials are Error coins. Why that some are designated Varieties in the CherryPicker's Guide is beyond me and beyond most Collectors and Coin Experts as the reason that the Designer's initials are missing is due to grease or debris clogging the Dies or due to over-polishing, over-grinding or other abrasion to the Dies during repairs and therefore, none of these constitute a planned Die modification or change by the Mints which would make them a Variety.
While in the past, some of these Error coins and so-called Variety coins have sold for significant premiums, the prices they fetch and interest in them has dropped significantly as collectors and wanna-be collectors have wised up to what the coins actually are. However, even though prices and interest in these Error coins has dropped significantly over the years, one can still get a nice premium for most of these and get prices well above the $0.01 that Pocket Change Searchers have invested in them!
Frank