For a client who wants to buy-and-hold precious metals as an inflation-hedge over the next five to 10 years, what's the most cost-effective way? The roundtrip cost of trading gold bullion bars, including transportation and storage, is estimated at about 0.5 percent per year over 10 years. This is approximately equal to the expense ratios of the leading precious metals ETFs for gold (GLD, 0.40 percent) and silver (SLV, 0.05 percent).

Another choice is to own shares of mining companies, but the uncertainties are great. As gold bullion has returned 12.2 percent annually for the past three years, the leading ETF of gold mining shares (GDX) has fallen by 4.6 percent per year due to mining operational risks and earnings disappointments. In February, the firm Gold Bullion International (GBI) announced a new platform for helping RIAs access gold, silver, platinum and palladium for clients. While this may become an attractive option for some, it appears to be more expensive to hold over time than GLD and SLV.

There is yet another choice that could be more economical than any of the above. It's a model called "streaming" pioneered by the company Silver Wheaton in 2004. Streaming companies pays an upfront fee to buy life of mine production (e.g., bullion) at a fairly low price. The two leading "streamers" in today's market are Silver Wheaton (SLW) and Sandstorm Gold (SAND).