When it comes to red wine, Spain provides more bang for the buck across the board than any other country. The reasons are many and varied: savvy, aggressive importers; a sun-splashed, dry climate; cheap labor and land costs; vastly improved winemaking techniques. But the biggest factor might be a variation of an old bromide:

Vines get better with age.

As they grow older, grapevines produce more concentrated fruit. That brings more depth of flavor to the bottle. And Spain not only has the world's most vineyards (15.5 percent of the planet's total), but also the most old-vine vineyards.

"Older vines and greater volume mean higher quality," said Brian Mallie, wine director for Kowalski's, "increasing the possibility of finding good quality grapes at what we consider jug-wine levels. At every price point you can find a better bottle than you can from California."

It doesn't hurt that most of Spain's vineyard land is long since paid for. In California's Central Coast region, by contrast, a person starting a 40-acre vineyard and building a winery would need 20.3 years just to get to the break-even point, according to Silicon Valley Bank's Rob McMillan.

So Spanish vintners not only can let their vines age gracefully, but they find it easier to afford newer technology in the winery. They also are not hidebound to "the more oak, the better" approach that dominated Iberia until fairly recently.

Not that there's anything wrong with oak. But some grapes play well with it while others not so much. And one of Spain's main strengths is the diversity of grapes. Tempranillo, the base for Rioja's world-class wines, still is king, but the royal court has grown exponentially.

Garnacha from Priorat, mencia from Bierzo, carigñena from Catalonia and monastrell from all over the south are among the rising stars. Having so many options made in many styles from 70 designated wine areas can be a bit dizzying. But it's a darn sight better than 10 or 15 years ago, when the Spanish offerings at stores and restaurants were basically take-Rioja-or-leave it.

"I'm hard pressed to hang my hat on any one region," said Mallie, who cited Monsant for "some pretty sexy wines," Campo de Borgia for garnacha and the entire south, where "[importer] Eric Solomon has brought in a lot of values."

Because of people like Solomon, consumers can do some handy-dandy shopping by the back label of wines, where names such as European Cellars, Jorge Ordóñez, De Maison, the Rare Wine Co. and Olé Imports can be indicators of quality and/or consistent style.

Some of those can be found among the wines below, which I have found exemplary for the prices:

$10 and under: Evodia Garnacha, Castillo de Monseran Garnacha or Carinena.

$15 and under: Atteca Garnacha Old Vines, Avante Tineta Ribera del Duero, Zestos Garnacha, Lo Nuevo Sorbo a Sorbo, Piñol Ludovicus.

$20 and under: Pasanau Priorat, Muriel Crianza Rioja, Ramón Bilbao Limited Edition Rioja, Palacios Remondo La Montesa and La Vendimia, Capcanes Costers del Gravet Montsant, La Cartuja Priorat.

$25 and under: Alvaro Palacios Camins del Priorat.

Over $25: Vina Ardanza La Rioja Alta, anything from Muga or Lopez de Heredia, El Nido Clio Jumilla, Numanthia Termes, Palacios Finca Dofi.

Oh, and if there's a better $12 red wine anywhere than the Olivares Altos de la Hoya Monastrell, I would love to hear about it.

Follow Bill Ward on Twitter: @billward4