According to The Wall Street Journal's Weekend Edition, investors are in for a treat:

A potentially cutthroat price war is shaping up between two of the biggest firms in the exchange-traded-fund business.

In coming weeks, Vanguard Group plans to roll out an ETF designed to directly undercut one of the biggest products on the market, from rival Barclays Global Investors, a unit of Barclays PLC (NYSE: BCS).

Vanguard is launching the Vanguard Europe Pacific ETF to track the MSCI EAFE index, which provides investors with broad exposure to developed-market equities.

The fund and its obscenely low 0.15% expense ratio take direct aim at Barclays' iShares MSCI EAFE ETF, which has an expense ratio of 0.35%.

Given that low expenses are perhaps the single greatest predictor of a fund's performance, this is awesome news for investors. Baseball speedsters like Kenny Lofton and Carl Crawford are often seen as reliable because it is said that "speed never goes into a slump." A power hitter like Barry Bonds or David Ortiz might lose his home run stroke for a while, but base-stealers can always run when healthy.

Low-expense funds are the Rickey Hendersons of personal finance, and as expense ratios continue their descent, investors will reap the rewards, although the profits of fund managers may decline.