Financial advisers are supposed to help you make money -- particularly when you're nearing retirement. But you could be misled, said CEO Jay Shah of Personal Capital, a San Carlos, California-based financial advisory firm, which just completed a study of 10 prominent advisory firms, its own included.

The result: Money management fees for some firms ranged up to 3 percent, while for others the fees were only 1 percent or less. When the fees were added up over an investing history of 44 years, the difference between an annual fee of 1 percent and 3 percent amounted to $400,000, or roughly the cost of an average home.

The survey didn't include the "hidden" charges for electronic funds transfer and wire fees, IRA and retirement plan fees, margin interest, depositary service fees charged by banks and account opening, closing and other transaction fees.

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Misperceptions about what you pay for advisory services -- and what you get for your money -- abound, according to the study. More than 60 percent of Americans surveyed didn't know how much they paid in investment fees, which isn't surprising given there are all sorts of wrinkles to consider, like "phantom gains." When a mutual fund buys and sells individual securities during a year, it's not responsible for paying the tax bill on any gains. That's passed along to the shareholders -- even though they never made the transaction.

Advisory firms often sell life insurance and annuities, products with a guaranteed return over time, which can add another 1 to 2 percent to their fees, Shah cautioned. He added that there are "stiff surrender clauses" if you pull the money out to meet an emergency.

While the Personal Capital survey presents a grim picture of its competitors, Personal Capital itself isn't at the lowest end of the cost spectrum, either. Vanguard and Charles Schwab (SCHW) come in with the lowest fees. But the nation's second-largest mutual fund manager, Fidelity, isn't even included because its many services made it impossible to do a direct "apples-to-apples" comparison when the survey was undertaken, Shah claimed.

The survey is partly a promotional tool for Personal Capital because it comes in below some heavyweight advisory firms like JPMorgan (JPM), Wells Fargo (WFC) and Morgan Stanley (MS). But it still claims to offer a level of service above its lower-cost competitors, particularly in terms of tax-planning and portfolio rebalancing.

The survey also acknowledged that the "fees" advisers charge are negotiable and don't necessarily reflect what everyone pays. And Shah agreed that for many people, having a financial adviser can be a necessity. "People need advice," said Shah. "Self-managers can make bad decisions."

To find a good financial adviser, Shah suggests you ask a series of questions designed to ferret out who's best interest the manager is acting in: