A Date set of $10 Liberties is not an extraordinarily difficult set, by virtue of the fact that during nearly all of their run, multiple mints were striking them each year. This allows the Registry participant a choice of coins for most years. For example the 1875-P $10 is an incredible rarity, but the 1875-CC, while quite scarce, can be had for a fraction of the price. That said, the early issues (1838 and 1839) were struck only in Philadelphia, and are a unique type. The late Civil War years (1863-65) are also tough, as are a short run of dates in the mid-1870s (1875-77) when it appears that nearly all of the gold output from the Philadelphia mint was being devoted to Double Eagles.