Rarity figures get published in books like the Cherrypicker's guide--but as actual finds change constantly, so does "rarity". Are you interested in value? Because rarity and value are often unrelated. There are some IHC RPDs where there are only a couple examples known, but since the demand is low, so is their value. Snow's books give star ratings, which is his way of approximating interest/value for each value. This 1891 RPD (Snow-3) is given 3 stars, which is translated to mean "A highly sought after variety with a premium between 3X and 5X". Still, what a collector will pay for any variety is based on interest and perceived "value", including prior sales figures (if you can find them). The little I know on value for specific varieties is based on research on auction sites, past ebay sales, and what variety dealers are selling--research that anyone can do. So putting a "value" on any coin is a guess--until it's sold. In the case of this variety, it's a great RPD and I've seen it bid up on eBay. If you got this one near the normal catalogue price--then you did well.
