I think the PCGS Price Guide is someone's wishful fantasy, perhaps conceived after four or five hours at an Irish bar on St. Paddy's day where drinks were two-for-one. Not only way overpriced in just about every grade in every issue (there are exceptions on a case by case basis), the PCGS Price Guide is also badly abused by sellers, especially those who slab their own coins, give them whatever grade they want, then quote the PCGS guide. As someone said, even PCGS-graded coins don't sell for what the Price Guide states as their value. As mentioned, there's always exceptions, particularly with very high grade and really scarce and rare coins.
Sure, I use it to give me an idea where a particular coin stands (worth just a few bucks or thousands?) and, over time whether a coin's value has gone up or down, but it sure isn't my price Bible. It's advantage is that it's online, downloads quickly, and in my bookmarks, so it's convenient for a fast lookup. I also use other online price guides, particularly the one below, along with Coin Values and Coin Prices magazines. I also use Heritage's realized prices for high grade coins and
ebay's completed auctions function to determine what price a particular coin has actually sold recently.
A more realistic guide is
http://www.coinvalues.us/ .