At an event I did for a client recently, I brought a wine that I had been eager to taste. The wine was priced at about ten times the least expensive wine on the table and almost three times the most expensive wine. I planted it, unbeknownst to my client, alongside the other wines and refused to answer any questions about wine prices until everything was tasted. When the tasting was completed, I shared the various prices with the group. The outcome of this experiment was that most people didn't notice a marked difference in quality between Wine X and the others. The lesson, I suggested, is that, when chosen skillfully, wine of substance and character can be found at many different price points.
Wines are priced based on a great many factors. Production costs, which include land, labor, barrels and other equipment, are a major factor, but don't make up the entire picture. Other factors can include marketing and branding costs, vine yield (determined both naturally or by dropping fruit to concentrate flavor in fewer berries), perceived quality in the marketplace (when was the last time you encountered a "cheap" wine from Champagne?), and, of course, supply and demand.
Given the high cost of land and labor (among other things) in the United States' best known wine growing regions, domestic values can be hard to come by. Elsewhere in the world, these costs are often much lower (save vineyards in famous regions like Burgundy), and there are even sometimes government subsidies in place to support agricultural enterprises - grape growers are framers, after all. Also, many producers around the world grow grape varieties that are not as well known as the big sellers in the USA... and, therefore, sometimes need to compete on price in order to get the consumer's attention.
So don't judge a wine by its price. It's been rare for me to encounter a $100 bottle that's been 10 times better than a $10 bottle. For help finding quality wines at lower prices (or avoiding high priced/overpriced ones) ask a wine profession you trust - I bet they'd be happy to help (I know I am)!