An inexpensive wine should have the same attributes as a pricey one: It should be balanced (meaning that no one characteristic like sweetness or acidity overwhelms everything else); it should suit the food you're serving; and, last but not least, the fifth sip should taste as good as the first. A wine that is cloying, acidic or simply bizarre is a bad buy whether it's $5 or $25. There are just too many great choices out there to settle for one that isn't delicious.
What makes a wine expensive? Some wines are expensive because they are sought after or have a track record for aging or resale value at auction. Fair enough. But plenty of wines are costly because the proprietor owes the bank big-time for his land or has a healthy ego or has simply decided that his wine will seem more appealing at $30 than at $15. It's amazing what a little blind tasting can do to assumptions about price tags.
Where can you find bargains? The hottest areas right now for high-quality, under-priced wines are Spain, southern Italy, Chile and Argentina. There are also still plenty of outstanding deals from southern France and Australia, particularly in reds.