There is no average because the prices listed in the Red Book are all over the map. Some are too high, others are too low, and some few may even be accurate. It's just like Goldilocks So just forget the prices listed in the Red Book and never pay any attention to them.
My opinion the redbook prices are high retail on many common coins and too low on much of the rarer and earlier stuff that trades much more infrequent and often collectors are willing to pay much more than "book" price for a coin that there's few opportunities to buy also neither takes in eye appeal where 2 coins of the same grade one with much more pleasing color or strike etc will bring much more then the other that's just something that's got to be considered in person I personally have paid 10 x and more greysheet for Morgan dollars with. Great toning and there were underbidders too the redbook though I use nearly daily primarily to look up mintage figures is handy for many things
The Red Book is great for historical information, original mintage information and mint specifications, but not so much for real world pricing. Still, it is a book I highly recommend.
I don't use the Red Book for pricing. I use some of my magazines and the NGC price guide, but I primarily rely on Heritage Auction archives.
The only thing you should use the prices for from the Redbook are to indicate general trends (This coin is higher priced than the others in all grades! It must be a better date) and sometimes for identifying condition rarities. (The rest of the coins go up moderately from this grade to that one, but this coin makes a much larger jump so it is probably scarcer in grades higher than that compared to the others.) As far as absolute prices go forget it. If you have a 2014 redbook, it's prices were compiled in 2012, the graysheet prices were compiled in the past week or so. Which do you think will be more accurate?
Agree with Doug and Tom--the Redbook isn't valuable as a price guide, but as a resource for collectors. Its historical data is fabulous, and the information and pictures are superb. It is great for mintage references, too. For pricing, use the Graysheet and the PCGS and NGC price guides--they show market trends, and not historical pricing.
Let's put it this way, I would put more trust in Grey Sheet than Red Book because Red Book is only an annual publication and Grey Sheet is published more frequently than that.
