The Schwab survey included 510 investors with a minimum of $250,000 in investable assets and at least $25,000 in bonds purchased in the last two years. The survey respondents averaged nearly $500,000 in bonds and had an average of $1.8 million in household savings and investable assets.

The survey shows only 35% of the investors believe they always get the best price from their bond broker, 40% say they don't know how to get the best price, and 40% say it's either too complicated or too time-consuming to shop for the best price.

Michael Martin, president and chief investment officer of Financial Advantage Inc. in Columbia, Md., says the bond industry is inherently less transparent than other investments. "The interest rate and credit quality are two drivers of the price, as well as the duration of the bond," he explains. "For bonds, the middleman is in the driver's seat and the client is in the dark." Martin says he doesn't see that situation changing anytime soon.

Mike Nozzarella, an advisor at The Tarbox Group in Newport Beach, Calif., says larger advisors have tools available to help them garner more information about bond transactions, but that the sector remains a black hole for most retail investors. "If you're buying a bond, there is no way of knowing what the broker bought it for or if they are taking it from their own inventory," he says. "It's just one of those areas where there's still little transparency for the individual investor."

Nozzarella says that the Municipal Securities Rulemaking Board is attempting to make more information available about municipal bonds on its Web site (http://emma.msrb.org). Even so, he adds, many investors might lack the background to evaluate the available information.

Crawford says Schwab is trying to make bond trading more transparent by providing comparisons of bond prices so investors can see what other firms are charging for the same bonds, making available trade history so that investors can see how the bond has traded, and being up front about its own mark-up of $1 per $1,000 bond on U.S. bonds.