America's foremost authority on wines offers the following on wine bargains: "One of the most gratifying aspects of being a wine critic is discovering those under-the-radar, superb wine bargains that taste as if they should cost two or three times the price but don't. ... The myth is that wines that cost $25 or less are worth just what you pay for them and are never terribly interesting. This is totally untrue, and with work, one can unearth these small treasures that deliver seriously good wine at remarkably fair prices." [Robert Parker, "Parker's Wine Bargains: The World's Best Wine Values under $25"]
I obviously agree with the points made by Parker, and I strongly recommend his book (list price $17.99, published in 2009). He provides a price range (under $15, $16-20, and $21-25) and a two-sentence description of the general characteristics of each wine, but he does not offer point values for specific wines and vintages in this book.
He includes over 2,500 wines under $25 from all regions of the world: Argentina, Australia, Austria, Chile, France, Germany, Greece, Italy, New Zealand, Portugal, South Africa, Spain, and the United States. Of the 497 page book, 178 pages are devoted to French wines, 58 pages to Italian wines, and 40 pages to U.S. wines.
Although most wines listed in Parker's book are still under $25, the prices of some wines have risen, and it may be difficult to find selected wines still selling for under $25. And the prices can vary widely according to vintage. For example, one of the best value-priced Bordeaux wines is from Chateau d'Aiguilhe (Cotes de Castillon). The 2006 and 2007 vintages were both priced $24.99 at K&L, while the superb 2005 vintage was $37.99 for a bottle of d'Aiguilhe.
For a much more detailed review of wines globally, see "Parker's Wine Buyer's Guide" (7th edition, 2008) which includes point values for specific vintages of thousands of wines. For an in-depth overview of the world of wine with discussion of countries producing value-priced wines, see "The Wine Bible" by Karen MacNeil (2001).