"You sold silver too soon," grumbled a client. "Look, it's almost $50 an ounce."

That was just one of the conversations I had with disgruntled investors only one week ago. There is no question I felt bad since I had advised readers to sell at least half their silver investments between $36 to $37 an ounce a few weeks ago. Beginning Monday, silver began to drop as the CME hiked margin requirements. By Friday, silver had dropped over 25 percent to as low as $33.05 and ounce.

Parabolic moves such as the kind we have had in silver, and to a lesser extent gold, always revert to the mean. I learned that lesson many times over 30 years of investing in commodities. My strategy is to pick a price level and stick with it, regardless of whether the commodity overshoots my target.

Oil was another commodity where I suggested investors take profits at $100 a barrel. It has subsequently climbed higher, overshooting my target by almost $14 a barrel before it, too, plummeted this week to $99 a barrel. I remain a seller until oil breaks $85 barrel on the downside.

Of course, now that precious metals are in free fall, the knee-jerk reaction from the uninitiated is "at what price do we get back in?"

The easy answer is: whenever investors stop asking that question. When the talking heads and strategists throw in the towel, when precious metals commercials disappear from the airwaves and nobody wants to be bothered with silver, only then will I be willing to reenter the precious metals.

Unfortunately, the sharp correction in silver as well as a bounce in the dollar has impacted the equity markets overall. That is unfortunate and yet for those with steady nerves and grim resolve it is an opportunity.

Most commodities have dropped along with gold and silver. That is understandable given that the majority of traders had purchased commodities on margin (borrowed money). When prices decline substantially (as they have this week) margin calls escalate and notices from lenders flow out through Wall Street like floodwaters through the Mississippi Delta. Margin lenders demand more collateral to maintain their loans to these silver speculators and they want this money immediately.

Speculators, caught with owing huge sums of margin money, did what they always do — sell other investments, usually their winners, to meet the margin call. Oil, gas, base metals, soft commodities — whatever they can sell — which increases the selling pressure on everything and the ripple effect soon reaches high flying stocks and finally equities in general. Welcome to today's markets.

For those of us with cooler heads and steadier nerves, treat this sell off as simply another gift horse in the making. And I'm not about to examine its mouth. I would be buying instead. You see, lower energy as well as other commodity prices are good for the global economy. At some point investors will wake up to that fact. In the meantime, expect more volatility.

"How low can we go?" asked several clients ranging from a doctor in Salisbury, Conn.,  to a retired engineer in Williamstown.

We're almost there, in my opinion. Let's call the low somewhere between 1,305 and 1,325 on the S&P 500 Index (and I may be too negative in my guess). If we dropped as low as 1,300, it would still only be a 5 percent correction from the top. Our last decline was about 7 percent. Since then we have powered as high as 1,370 on the S&P (the intraday high reached on May 2). Remember, you should expect at least three pullbacks a year in the stock market of up to 5 percent. This is simply one of them and the cost of doing business in the stock market.

Bill Schmick is an independent investor with Berkshire Money Management. (See "About" for more information.) None of the information presented in any of these articles is intended to be and should not be construed as an endorsement of BMM or a solicitation to become a client of BMM. The reader should not assume that any strategies, or specific investments discussed are employed, bought, sold or held by BMM. Direct your inquiries to Bill at (toll free) or e-mail him at wschmick@fairpoint.net. Visit www.afewdollarsmore.com for more of Bill's insights.